back to indexThe Science of Hearing, Balance & Accelerated Learning | Huberman Lab Podcast #27
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Welcome to the Huberman Lab Podcast,
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where we discuss science and science-based tools
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for everyday life.
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I'm Andrew Huberman,
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and I'm a professor of neurobiology and ophthalmology
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at Stanford School of Medicine.
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Today, we're going to talk all about hearing and balance
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and how you can use your ability to hear specific things
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and your balance system in order to learn anything faster.
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The auditory system, meaning the hearing system,
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and your balance system,
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which is called the vestibular system,
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interact with all the other systems of the brain and body
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and used properly can allow you
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to learn information more quickly,
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remember that information longer and with more ease,
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and you can also improve the way you can hear.
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You can improve your balance.
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We're going to talk about tools for all of that.
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This is one area of science where we understand a lot
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about the cells and the mechanisms in the ear
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and in the brain and so forth,
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so we're going to talk about that a little bit,
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and then we're going to get directly into protocols,
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We're also going to talk about ways
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in which the auditory and balance systems suffer.
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We're going to talk about tinnitus,
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which is this ringing of the ears that,
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unfortunately for people that suffer from it,
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they really suffer.
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It's very intrusive for them.
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We're going to talk about some treatments that can work
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in some circumstances
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and some of the more recent emerging treatments
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that I think many people aren't aware of.
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We're also going to talk about this,
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what seems like kind of a weird fact,
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which is that 70% of people, all people,
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make what are called autoacoustic emissions.
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Their ears actually make noises.
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Chances are your ears are making noises right now,
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but you can't perceive them,
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and yet those can have an influence on other people
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and animals in your environment.
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It's a fascinating aspect to your biology.
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You're going to learn a lot about how your biology
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and brain and ears and the so-called inner ear
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that's associated with balance,
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you're going to learn a lot about how all those work.
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You're going to learn a lot of neuroscience.
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I'll even tell you what type of music to listen to,
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and if you listen to me,
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you can leverage that in order to learn faster.
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Before we begin talking about the science
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of hearing and balance and tools
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that leverage hearing and balance for learning faster,
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I want to provide some information
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about another way to learn much faster.
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There's a paper that was published recently.
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This is a paper that was published in Cell Reports,
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an excellent journal.
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It's a peer-reviewed paper from a really excellent group
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looking at skill learning.
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Now, previously, I've talked about
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how in the attempt to learn skills,
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the vital thing to do is to get lots of repetitions.
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You've heard of the 10,000 hours thing.
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You've heard of lots of different strategies
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for learning faster, 80-20 rule and all that.
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The bottom line is you need to generate
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many, many repetitions of something
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that you're trying to learn,
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and the errors that you generate
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are also very important for learning.
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It also turns out that taking rest
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within the learning episode is very important.
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I want to be really clear what I'm referring to here.
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In earlier episodes,
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I've discussed how when you're trying to learn something,
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it's beneficial, it's been shown in scientific studies,
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that if you take a 20-minute shallow nap
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or you simply do nothing after a period of learning,
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that it enhances the rates of learning
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and the depth of learning,
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your ability to learn and remember that information.
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What I'm about to describe are new data
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that say that you actually should be injecting rest
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within the learning episode.
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I'm not talking about going to sleep while learning.
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This is the way that the study was done.
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The study involved having people
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learn sequences of numbers or keys on a piano.
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So let's use the keys on a piano example.
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I'm not a musician, but I think I'll get this correct.
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They asked people to practice a sequence of keys,
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G-D-F-E-G, G-D-F-E-G, G-D-F-E-G,
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and they would practice that either continually
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for a given amount of time,
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or they would just do that for 10 seconds.
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They would play G-D-F-E-G, G-D-F-E-G, G-D-F-E-G,
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G-D-F-E-G for 10 seconds,
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and then they would take a 10-second pause, a rest.
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They would just take a space or a period of time
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where they do nothing for 10 seconds.
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Then they would go back to G-D-F-E-G, G-D-F-E-G.
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So the two conditions essentially
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were to have people practice continually,
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lots of repetitions, or to inject or insert
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these periods of 10 seconds idle time
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where they're not doing anything,
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they're not looking at their phone,
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they're not focusing on anything,
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they're just letting their mind drift
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wherever it wants to go,
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and they are not touching the keys on the keyboard.
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What they found was that the rates of learning,
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the skill acquisition and the retention of the skills
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was significantly faster
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when they injected these short periods of rest,
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these 10-second rest periods.
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And the rates of learning were,
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when I say significantly faster, were much, much faster.
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I'll reveal what that was in just a moment.
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But you might ask, why would this work?
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Why would it be that injecting these 10-second rest periods
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would enhance rates of learning?
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What they called them was micro-offline gains
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because they're sort of taking their brain offline
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from the learning task for a moment.
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Well, it turns out the brain isn't going offline at all.
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You've probably heard of the hippocampus,
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the area of the brain involved in memory,
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and the neocortex, the area of the brain
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that's involved in processing sensory information.
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Well, it turns out that during these brief periods of rest,
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these 10-second rest periods,
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the hippocampus and the cortex are active in ways
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such that you get a 20-times repeat of the GDFEG.
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It's a temporal compression, as they say.
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So basically, the rehearsal continues while you rest,
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but at 20 times the speed.
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So if you were normally getting just, let's just say,
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five repetitions of GDFEG, GDFEG, GDFEG per 10 seconds,
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now you multiply that times 20.
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In the rest periods, you've practiced it 100 times.
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Your brain has practiced it.
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We know this because they were doing brain imaging,
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functional imaging of these people with brain scanners
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while they were doing this.
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This is an absolutely staggering effect.
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And it's one that, believe it or not,
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has been hypothesized or thought to exist
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for a very long time.
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This effect is called the spacing effect,
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and it was actually first proposed by Ebington in 1885.
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And since then, it's been demonstrated
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for a huge number of different what they call domains,
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in the cognitive domain, so for learning languages,
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in the physical domain, so for learning skills
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that involve a motor sequence.
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It's been demonstrated for a huge number
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of different categories of learning.
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If you want to learn all about the spacing effect
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and the categories of learning that it can impact,
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there's a wonderful review article.
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I'll provide a link to it.
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The title of the review article is
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Parallels Between Spacing Effects During Behavioral
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and Cellular Learning.
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What that review really does is it ties
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the behavioral learning and the improvement of skill
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to the underlying changes in neurons
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that can explain that learning.
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I should mention that the paper that I'm referring to,
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the more recent paper that injects these 10-second
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little micro offline gains rest periods,
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is the work of the laboratory of Leonard Cohen,
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not the musician Leonard Cohen.
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He passed away, he was not a neuroscientist,
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a wonderful poet and musician, but not a neuroscientist.
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Again, the paper was published in Cell Reports,
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and we will provide a link to the full paper as well.
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So the takeaway is if you're trying to learn something,
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you need to get those reps in,
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but one way that you can get 20 times the number of reps in
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is by injecting these little 10-second periods
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Again, during those rest periods,
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you really don't want to attend to anything else
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as much as possible.
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You could close your eyes if you want,
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or you can just simply wait and then get right back
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into generating repetitions.
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I find these papers that Cell Reports and other journals
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have been publishing recently to be fascinating
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because they're really helping us understand
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what are the best protocols for learning anything,
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and they really leverage the fact
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that the brain is willing to generate repetitions for us,
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provided that we give it the rest that it needs.
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So inject rest throughout the learning period,
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and if you can, based on the scientific data,
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you would also want to take a 20-minute nap
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or a 20-minute decompressed period
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where you're not doing anything after a period of learning.
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I think those could both synergize
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in order to enhance learning even further,
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although that hasn't been looked at yet.
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Before we begin talking about hearing and balance,
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I just want to mention that this podcast is separate
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from my teaching and research roles at Stanford.
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It is, however, part of my desire and effort
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to bring zero cost to consumer information about science
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and science-related tools to the general public.
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In keeping with that theme,
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I want to thank the sponsors of today's podcast
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and make it clear that we only work with sponsors
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whose products we absolutely love
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and that we think you will benefit from as well.
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Our first sponsor is Roca.
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Roca makes sunglasses and eyeglasses
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that, in my opinion, are the very highest quality available.
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The company was founded by two All-American swimmers
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from Stanford, and everything about their eyeglasses
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and sunglasses were created with performance in mind.
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These eyeglasses and sunglasses have a number of features
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that really make them unique.
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First of all, they're extremely lightweight.
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The optical clarity of the lenses is spectacular.
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And for the sunglasses,
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they have this really great feature,
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which is as you move in and out of shadows
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or as across the day, the amount of sunshine might change,
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you always experience the world as clear and bright.
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And that can only come from really understanding
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how the visual system works.
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The visual system has all these mechanisms
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for adaptation and habituation.
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You don't need to know how those things work,
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but the folks at Roca clearly do
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One thing that I really like
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If you'd like to try Roca eyeglasses,
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Okay, well, if you can hear me, that's amazing,
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because what it means is that my voice
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is causing little tiny changes in the airwaves,
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wherever you happen to be,
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and that your ears and whatever's contained in those ears
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and in your brain can take those sound waves
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and make sense of them,
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and that is an absolutely fantastic
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and staggering feat of biology,
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and yet we understand a lot about how that process works.
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So I'm going to teach it to you now in simple terms
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over the next few minutes.
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So what we call ears have a technical name.
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That technical name is oracles,
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but more often they're called pinna.
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The pinna is P-I-N-N-A, pinna,
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and the pinna of your ears,
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this outer part that is made of cartilage and stuff,
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is a range such that it can capture sound
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in the best way for your head size.
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We're going to talk about ear size also,
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because it turns out that your ears change size
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across the lifespan and that how big your ears are,
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or rather how fast your ears are changing size
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is a pretty good indication of how fast you're aging.
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So we'll get to that in a few minutes,
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but I want to talk about these things that we call ears
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and some of the stuff contained within them
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that allow us to hear.
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So the shape of these ears that we have
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is such that it amplifies high frequency sounds.
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High frequency sounds as the name suggests
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is the squeakier stuff, right?
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So low frequency sound.
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Costello snoring in the background,
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that's a low frequency sound or high frequency sound, okay?
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So we have low frequency sounds and high frequency sounds
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and everything in between.
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Now those sound waves get captured by our ears
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and those sound waves,
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for those of you that don't
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maybe fully conceptualize sound waves
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are literally just fluctuations or shifts
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in the way that air is moving
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toward your ear and through space.
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In the same way that water can have waves,
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the air can have waves, okay?
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So it's reverberation of air.
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Those come in through your ears
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and you have what's called your eardrum.
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And on the inside of your eardrum,
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there's a little bony thing
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that's shaped like a little hammer.
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So attached to that eardrum,
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which can move back and forth like a drum,
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it's like a little membrane,
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you've got this hammer attached to it.
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And that hammer has three parts.
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For those of you that want to know,
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those three parts are called malleus, incus, and stapes.
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But basically you can just think about it as a hammer.
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So you've got this eardrum and then a hammer,
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and then that hammer has to hammer on something.
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And what it does is it hammers on a little coiled piece
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of tissue that we call the cochlea,
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sometimes called the cochlea,
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depending on where somebody lives in the country.
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So typically in the Midwest, on the East Coast,
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they call them cochlea.
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And on the West Coast, we call them cochlea.
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So the snail-shaped structure in your inner ear
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is where sound gets converted into electrical signals
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that the brain can understand.
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But I want to just bring your attention to that little hammer
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because that little hammer is really, really cool.
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What it means is that sound waves come in through your ears.
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That's what's happening right now.
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That eardrum that you have, it's like the top of a drum.
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It's like a membrane, or it can move back and forth.
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It's not super rigid.
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And it moves that little hammer,
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and then the hammer goes dung, dung, dung, dung, dung,
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and hits this coil-shaped thing
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that we're calling the cochlea, okay?
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Now, the cochlea at one end is more rigid than the other.
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So one part can move really easily,
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and the other part doesn't move very easily.
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And that turns out to be very important
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for decoding or separating sounds that are low frequency,
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like Costello's snoring,
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and sounds that are of high frequency,
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like a shriek or a shrill.
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And that's because within that little coiled thing
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we call the cochlea,
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you have all these tiny little,
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what are called hair cells.
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Now, they look like hairs,
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but they're not at all related to the hairs on your head
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or elsewhere on your body.
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They're just shaped like hairs, so we call them hair cells.
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Those hair cells, if they move,
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send signals into the brain
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that a particular sound is in our environment.
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And if those hair cells don't move,
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it means that particular sound is not in our environment,
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So just to give you the mental picture of this,
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sound waves are coming in
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because there's stuff out there making noises like my voice.
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It's changing the patterns of air around you
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in very, very subtle ways.
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That information is getting funneled into your ears
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because your pinna's are shaped in a particular way.
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The eardrum then moves this little hammer
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and the hammer bangs on this little snail-shaped thing.
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And because that snail-shaped thing at one end
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is very rigid, it doesn't want to move.
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And at the other end, it's very flexible.
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It can separate out high-frequency and low-frequency sounds.
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And the fact that this thing in your inner ear
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that we call the cochlea is coiled
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is actually really important to understand
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because along its length,
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it varies in how rigid or flexible it is.
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I already mentioned that before.
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And at the base, it's very rigid.
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And that's where the hair cells, if they move,
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will make high-frequency sounds.
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And at the top, what's called the apex,
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it's very flexible and it's more like a bass drum.
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So basically what happens is sound waves come into your ears
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and then at one end of this thing that we call the cochlea,
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at the top, it's essentially encoding
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or only responding to sounds that are like,
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doom, doom, doom, doom.
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Whereas at the bottom, it responds to high-frequency sounds
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like a cymbal, tss, tss, tss, tss, tss, tss.
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Okay, and everywhere in between,
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we have other frequencies, medium frequencies.
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Now, this should stagger your mind.
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If it doesn't already, it should.
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Because what this means is that
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everything that's happening around us,
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whether or not it's music or voices or crying or screaming
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or screaming of delight from small children
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who are excited because they're playing
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or because they get cake,
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all of that is being broken down into its component parts.
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And then your brain is making sense of what it means.
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These things that I've been talking about,
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like the pinna of your ears and this little hammer
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and the cochlea, that's all purely mechanical.
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It has no mind of its own.
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It's just breaking things down into high frequencies,
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medium frequencies, and low frequencies.
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And if you don't understand sound frequency,
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it's really simple to understand.
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Just imagine ripples on a pond.
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And if those ripples are very close together,
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that's high frequency.
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They occur at high frequency.
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If those ripples are further apart, it's low frequency.
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And obviously, medium frequency is in between.
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So just like you can have waves in water,
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you can have waves in air.
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So that's really how it works.
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Now, we are all familiar with light
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and how if you take a prism and put it in front of light,
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it will split that light into its different wavelengths,
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its different colors, red, green, blue, et cetera, right?
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So like the Pink Floyd, Dark Side of the Moon album,
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I think has a prism and it's converting white light
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into all the colors,
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all the wavelengths that are contained in white light.
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Your cochlea essentially acts as a prism.
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It takes all the sound in your environment
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and it splits up those sounds into different frequencies.
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So you can think of the cochlea of your ear
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sort of like a prism.
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And then the brain takes that information
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and puts it back together and makes sense of it.
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So those hair cells in each of your two cochlea,
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because you have two ears, you also have two cochlea,
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send little wires, what we call axons,
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that convey their patterns of activity into the brain.
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And there are a number of different stations
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within the brain that information arrives at
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before it gets up to the parts of your brain
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where you are consciously aware.
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And because some of you have asked for more names
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in nomenclature, I'll give that to you.
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If you don't want a lot of detailed names,
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you can just ignore what I'm about to say.
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But basically the cochlea send information
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to what's called the spiral ganglion.
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The spiral ganglion, a ganglion, by the way,
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if you're going to learn any neuroscience,
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just know that anytime you hear ganglion,
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a ganglion is just a clump.
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So it means a bunch of neurons.
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So a clump of cells.
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So the spiral ganglion is a bunch of neurons
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that the information then goes off to
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what are called the cochlear nuclei in the brainstem.
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Brainstem is kind of down near your neck.
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Then up to a structure that has a really cool name
link |
called the superior olive
link |
because you have one on each side of your brain.
link |
And if I were to bring you to my lab
link |
and show you the superior olives in your brain
link |
or anyone else's brain, they look like little olives.
link |
They even have a little divot in them
link |
that to me looks like a pimento,
link |
but they just call them the superior olive.
link |
And then the neurons in the superior olive,
link |
then they send information up to what's called
link |
the inferior colliculus, only called inferior
link |
because it sits below a structure
link |
called the superior colliculus.
link |
And then the information goes up
link |
to what's called the medial geniculate nucleus
link |
and then up to your neocortex
link |
where you make sense of it all.
link |
Now you don't have to remember all that,
link |
but you should know that there are a lot of stations
link |
in which auditory information is processed
link |
before it gets up to our conscious detection.
link |
And there is a good reason for that,
link |
which is that more important than knowing what you're hearing
link |
you need to know where it's coming from.
link |
It's vital to our survival that if something,
link |
for instance, is falling toward us,
link |
that we know if it's coming to our right side,
link |
if it's going to hit us from behind,
link |
we have to know, for instance,
link |
if a car is coming at us from our left or from our right,
link |
and our visual system can help with that,
link |
but our auditory and our visual system collaborate
link |
to help us find and locate the position of things in space.
link |
That should come as no surprise.
link |
If you hear somebody talking off to your right,
link |
you tend to turn to your right, not to your left.
link |
If you see somebody's mouth moving in front of you,
link |
you tend to assume that the sound
link |
is going to come from right in front of you.
link |
Disruptions in this auditory hearing and visual matching
link |
are actually the basis of what's called
link |
the ventriloquism effect,
link |
which we'll talk about in a few minutes in more depth,
link |
but the ventriloquism effect can basically be described
link |
in simple terms as when you essentially think
link |
that a sound is coming from a location
link |
that it's not actually coming from.
link |
We'll talk about that in a moment,
link |
but what I'd like you to realize
link |
is that one of these stations deep in your brainstem
link |
is responsible for helping you identify
link |
where sounds are coming from
link |
through a process that's called interaural time differences.
link |
And that sounds fancy,
link |
but really the way you know where things are coming from,
link |
what direction a car or a bus or a person is coming from
link |
is because the sound lands in one ear before the other.
link |
And you have stations in your brain,
link |
meaning you have neurons in your brain
link |
that calculate the difference in time of arrival
link |
for those sound waves in your right versus your left ear.
link |
And if they arrive at the same time,
link |
you assume that thing is making noise right in front of you.
link |
If it's off to your right,
link |
you assume it's over on your right.
link |
And if the sound arrives first to your left ear,
link |
you assume quite correctly
link |
that the thing is coming toward your left ear.
link |
So it's a very simple and kind of mechanical system
link |
at the level of sound localization.
link |
But what about up and down?
link |
If you think about it,
link |
a sound coming from above is going to land on your right ear
link |
and your left ear at the same time.
link |
A sound from below is going to land on your right ear
link |
and your left ear at the same time.
link |
So the way that we know where things are
link |
in terms of what's called elevation,
link |
where they are in the up and down plane
link |
is by the frequencies.
link |
The shape of your ears actually modifies the sound
link |
depending on whether or not it's coming straight at you
link |
from the floor or from high above.
link |
And so already at the level of your ears,
link |
you are taking information about the outside world
link |
and determining where that information is coming from.
link |
Now, this all happens very, very fast and subconscious,
link |
but now you know why.
link |
If people really want to hear something,
link |
they make a cup around their ear.
link |
They essentially make their ear
link |
into more of a fennec fox type ear.
link |
If you've ever seen those cute little fennec fox things,
link |
they have these big spiky ears.
link |
They kind of look like a French bulldog,
link |
although they're kind of the fox version of the French bulldog
link |
with these big, tall ears,
link |
and they have excellent sound localization.
link |
And so when people lean in with their hand like this,
link |
if you're listening to this,
link |
I'm just cupping my hand at my ear,
link |
I'm giving myself a bigger pinna.
link |
Okay, and if I do it on the left side, I can do this side.
link |
And if I really want to hear something,
link |
I do it on both sides, okay?
link |
So this isn't just gesturing.
link |
This actually serves a mechanical role.
link |
And actually, if you want to hear where things are coming from
link |
with a much greater degree of accuracy,
link |
this can actually help
link |
because you're capturing sound waves
link |
and funneling them better.
link |
It's really remarkable, this whole system.
link |
So you've got these two ears,
link |
and because of the differences in the timing
link |
of when things arrive in those two ears,
link |
as well as these differences in the frequencies
link |
that certain things sound, or I should say,
link |
the differences in the frequencies
link |
that arrive at your ears,
link |
depending on whether or not the thing is above you
link |
or right in front of you or below you,
link |
you're able to make out
link |
where things are in space pretty well.
link |
So now you're probably starting to realize
link |
that these two things on the side of our head
link |
that we call ears are there for a lot more
link |
than hanging earrings on or for other aesthetic purposes
link |
or for putting sunglasses on top of.
link |
They are very powerful devices
link |
for allowing us to capture sound waves from our environment.
link |
Now I have a question for you,
link |
which is, can you move your ears?
link |
Turns out that unlike other animals,
link |
humans are not terrifically good at moving their ears.
link |
Other animals can move their ears even independently.
link |
So Costello is pretty good at raising his ears,
link |
the two of them together.
link |
He can't really move his ears separately.
link |
Some dogs can do that really well.
link |
In fact, sighthounds and some scent hounds
link |
do that exquisitely well.
link |
Some animals like deer and other animals
link |
that really have very acute hearing
link |
will put one ear down to a very particular angle
link |
and will tilt the other one
link |
and they will actually capture information
link |
about two distant sound-making organisms.
link |
Those could be hunters coming after them
link |
or other animals coming after them.
link |
They are very good at doing this.
link |
We're not so good at it,
link |
but about 60% of people it's thought
link |
can move their ears consciously
link |
without having to touch their ears.
link |
So can you do that?
link |
Maybe you should try it.
link |
Ask someone to look at you
link |
and see whether or not you can do it.
link |
The typical distances that people can move it
link |
is usually no more than two or three millimeters.
link |
It's subtle, but can you flap your pinna
link |
with just using mental control?
link |
If you can, or if you can't,
link |
try looking all the way to your right
link |
or all the way to your left.
link |
Obviously, if you're driving a car
link |
or doing something or exercising,
link |
don't put yourself in danger right now,
link |
but if you move your eyes all the way to your left,
link |
which I'm doing now, or all the way to my right,
link |
you might feel a little bit of a contraction of the muscles.
link |
It's that control ear movement, all right?
link |
Now I want to ask you this.
link |
Can you raise one eyebrow?
link |
I'm not very good at it.
link |
I can do a little bit,
link |
but it's mostly by like cramping down my face on one side
link |
and I certainly can't raise my right eyebrow.
link |
I can only do my left eyebrow.
link |
I'm trying to talk while I'm doing this,
link |
so this is why it looks strange.
link |
People who can raise one eyebrow very easily
link |
almost always can move their ears
link |
without having to touch them.
link |
It's controlled by the same motor pathway.
link |
And there does seem to be a small
link |
but statistically significant sex difference
link |
in the ability to move one's ears.
link |
Typically, men can do this more than women can,
link |
although plenty of women can move their ears as well.
link |
Now, if you think that is all a little strange or off topic,
link |
it's not because what we're really talking about here
link |
is a system of the brain,
link |
but also of the body of the musculature
link |
for localizing things in space.
link |
And so you might find it interesting to note
link |
that one of the things that we share very closely
link |
with other primates, with non-human primates,
link |
like macaque monkeys and chimpanzees,
link |
if you look at their ears, their ears are remarkably similar
link |
to our ears, or rather,
link |
our ears are remarkably similar to their ears.
link |
The eyes of certain monkeys like macaque monkeys
link |
are remarkably similar to human eyes.
link |
This is one of the reasons why
link |
if you look at a baby macaque monkey,
link |
it has this unbelievably human element to it.
link |
But the ears of these primates is very similar to our ears,
link |
our ears similar to their ears.
link |
If you're interested in ear movements
link |
and what they could mean,
link |
and some of the things that ear movements correlate with
link |
in other aspects of our biology,
link |
there's a nice paper, actually, a scientific paper.
link |
The author's last name is Code, C-O-D-E.
link |
It was published in 1995.
link |
I'll give a reference to that.
link |
It's a review article that discusses
link |
some of the sex differences in ear movement control,
link |
as well as the relationship between ear movements
link |
and eye movements.
link |
And it's a pretty accessible paper.
link |
It's one that I think any of you
link |
who are interested in this topic could parse fairly easily.
link |
And there's some very interesting underlying biology
link |
and some theories as to why humans would have
link |
this so-called vestigial or ancient carryover of a system
link |
for moving our ears.
link |
Now, if ear movement seems strange,
link |
next I want to talk about a different feature
link |
of your hearing and ears
link |
that's even stranger,
link |
but that has some really interesting implications
link |
And I'm guessing that you've not heard of this.
link |
What I'm about to describe are called
link |
autoacoustic emissions.
link |
And autoacoustic emissions, as the name suggests,
link |
are sounds that your ears make.
link |
Believe it or not, 70% of people
link |
make noises with their ears,
link |
but they don't actually detect them.
link |
Like I said, you've never heard of this.
link |
Okay, that's not what I mean.
link |
But what I do mean is that 70% of people's ears
link |
are making noise that's cast out of the ear.
link |
And these autoacoustic emissions
link |
actually can be detected by microphones.
link |
Sometimes they can be detected by other people in the room
link |
if they have very good hearing.
link |
Now, it turns out that women,
link |
or I should be technical here,
link |
females who report themselves as heterosexual
link |
have a higher frequency, not frequency of sound,
link |
but a higher frequency of autoacoustic emissions
link |
than do men who report themselves as heterosexual.
link |
Women who report themselves as homosexual or bisexual
link |
make fewer autoacoustic emissions than heterosexual women.
link |
These are data that come from Dennis McFadden's lab
link |
at the University of Texas, Austin.
link |
He actually discovered these
link |
what are called sexual dimorphisms
link |
and differences based on sexual orientation
link |
without looking for them.
link |
He was studying hearing.
link |
He's a auditory scientist.
link |
And people were coming into his laboratory
link |
and they were detecting these autoacoustic emissions
link |
and they started to notice the group differences
link |
in autoacoustic emissions.
link |
So they started asking people about their sex
link |
and about their sexual orientation.
link |
And these differences fell out of the data, as we say.
link |
And it's interesting because autoacoustic emissions
link |
are not something that we associate with sex
link |
or sexual dimorphism,
link |
but what these data really underscore is, first of all,
link |
a lot of us are making noises with our ears,
link |
some of us more than others,
link |
and that exposure to certain combinations
link |
of hormones during development
link |
are very likely shaping the way that our hearing apparati,
link |
meaning the cochlea and the pinna and all sorts of things,
link |
how those develop and how those function
link |
throughout the lifespan.
link |
We did do an episode on hormones and sexual development,
link |
which gets much deeper into the other effects
link |
that hormones have on the developing brain and body.
link |
If you want to check out that episode,
link |
we will put a link to it in the captions.
link |
So now I want to shift to talking about
link |
ways to leverage your hearing system, your auditory system,
link |
so that you can learn anything,
link |
not just auditory information,
link |
but anything faster.
link |
I get a lot of questions about so-called binaural beats.
link |
Binaural beats, as their name suggests,
link |
involve playing one frequency of sound to one ear
link |
and a different frequency of sound to the other ear.
link |
So it might be doon, doon, doon, doon
link |
to your right ear,
link |
and it might be doon, doon, doon, doon, doon, doon,
link |
And the idea is that the brain will take
link |
those two frequencies of sound
link |
and because the pathways that bring information
link |
from the ears into the brain eventually cross over,
link |
they actually share that information
link |
with both sides of the brain,
link |
that the brain will average that information
link |
and come up with a sort of intermediate frequency.
link |
And the rationale is that those intermediate frequencies
link |
place the brain into a state that is better for learning.
link |
And when I say better for learning,
link |
I want to be precise about what I mean.
link |
That could mean more focus for encoding
link |
or bringing the information in.
link |
As you may have heard me say before,
link |
we have to be alert and focused in order to learn.
link |
There is no passive learning
link |
unless we're little tiny infants.
link |
So can binaural beats make us more focused?
link |
Can binaural beats allow us to relax more if we're anxious?
link |
I know some people, they go to the dentist
link |
and the dentist offers binaural beats
link |
as they drill into your teeth and give root canals
link |
and things of that sort,
link |
probably causing some anxiety
link |
just describing those things right now.
link |
But those are available in many dental practices.
link |
Their binaural beats have been thought
link |
to increase creativity,
link |
or at least have been proposed to increase creativity.
link |
So what are the scientific data say about binaural beats?
link |
There are a number of different apps out there
link |
that offer binaural beats.
link |
There are a number of different programs.
link |
I think you can also even just find these
link |
on YouTube and on the internet,
link |
but typically it's an app and you'll program in
link |
a particular outcome that you want,
link |
more focused, more creative, fall asleep,
link |
less anxious, et cetera.
link |
So what are the scientific data say?
link |
So believe it or not, the science on binaural beats
link |
is actually quite extensive and very precise.
link |
So sound waves are measured typically
link |
in hertz or kilohertz.
link |
I know many of you aren't familiar
link |
with thinking about things in hertz or kilohertz,
link |
but again, just remember those waves on a pond,
link |
those ripples on a pond,
link |
if they're close together, then they are of high frequency.
link |
And if they're far apart, then they are low frequency.
link |
So when you hear more hertz,
link |
what you're essentially hearing is higher frequency, right?
link |
And so if it's many more kilohertz,
link |
then it's much higher frequency
link |
than if it's fewer hertz or kilohertz.
link |
And so you may have heard of these things
link |
as delta waves or theta waves or alpha waves
link |
or beta waves, et cetera.
link |
Delta waves would be big, slow waves, so low frequency.
link |
And indeed, there is quality evidence
link |
from peer-reviewed studies that are not sponsored
link |
by companies that make binaural beat apps
link |
that tell us that delta waves like one to four hertz,
link |
so very low frequency sounds, think Costello's snoring,
link |
can help in the transition to sleep and for staying asleep.
link |
And that theta rhythms,
link |
which are more like four to eight hertz,
link |
can bring the brain into a state of subtle sleep
link |
or meditation, so deeply relaxed, but not fully asleep.
link |
And then you can sort of ascend the staircase of findings
link |
here, so to speak, and you'll find evidence
link |
that alpha waves, eight to 13 hertz,
link |
can increase alertness to a moderate level.
link |
That's a great state for the brain to be in
link |
for recall of existing information, okay?
link |
And that beta waves, 15 to 20 hertz,
link |
are great for bringing the brain into focus states
link |
for sustained thought or for incorporating new information,
link |
and especially gamma waves, the highest frequency,
link |
the most frequent ripples of sound, so to speak,
link |
32 to 100 hertz for learning and problem solving.
link |
Now, all of this matches, or I should say maps
link |
onto what I've said before about learning really nicely,
link |
which is that you need to be in a highly alert state
link |
in order to bring new information in
link |
in order to access a state of mind
link |
in which you can tell your brain,
link |
or the brain is telling itself, okay, I need to learn this.
link |
This is why stress and unfortunate circumstances
link |
are so memorable is because our brain gets
link |
into a really high alert system.
link |
Here, we're talking about the use of binaural beats
link |
in order to increase our level of alertness
link |
or our level of calmness.
link |
Now, that's important to underscore
link |
because it's not that there's something
link |
fundamentally important about the binaural beats.
link |
They are yet another way of bringing the brain
link |
into states of deep relaxation through low-frequency sound
link |
or highly alert states for focused learning
link |
with more high-frequency sound.
link |
So they are effective,
link |
and I'll review a little bit of the data in detail.
link |
They're effective,
link |
but it's not that they're uniquely special for learning.
link |
It's just that they can help some people
link |
bring their brain into the state
link |
that allows them to learn better.
link |
So there are a lot of studies that allowed us to arrive,
link |
or I should say allowed the field to arrive
link |
on these parameters of slow, low-frequency waves
link |
are going to bring you into relaxed states,
link |
high-frequency waves into more alert states.
link |
There's very good evidence for anxiety reduction
link |
from the use of binaural beats.
link |
And what's interesting is the anxiety reduction
link |
seems to be most effective when the binaural beats
link |
are bringing the brain into delta,
link |
so those slow, big waves like sleep, theta, and alpha states.
link |
And I'll link to a couple of these studies,
link |
although I will probably link more to the list
link |
that really segregates them out one by one
link |
so you can see them all next to one another.
link |
There's good evidence that binaural beats
link |
can be used to treat pain, chronic pain.
link |
There's three studies in peer-reviewed journals,
link |
which I took a look at, and they seem to be of good quality,
link |
not sponsored research, as we say,
link |
not paid for by any specific company.
link |
Binaural beats have been shown
link |
to modestly improve cognition, attention,
link |
working memory, and even creativity.
link |
But the real boost from binaural beats
link |
appears to be for anxiety reduction and pain reduction.
link |
Some people might find these beneficial
link |
for these oral surgeries, right?
link |
Believe it or not, there are people who would rather
link |
have the entire root canal or cavity drilled
link |
without Novocain, and that's because they sometimes
link |
have a syringe phobia or something of that sort,
link |
or they just don't like being numb from the Novocain,
link |
or maybe there's an underlying medical reason.
link |
But I think most people don't enjoy
link |
getting their teeth drilled,
link |
even if they have Novocain in there or a root canal.
link |
And so it seems that binaural beats
link |
can be effective in that environment,
link |
and you don't have to go into that sort of
link |
extreme environment to benefit from binaural beats.
link |
Binaural beats are either
link |
relatively inexpensive thing to access.
link |
Most of the apps are pretty inexpensive.
link |
I don't have a favorite binaural beats app
link |
to recommend to you.
link |
I confess I did use binaural beats a few years ago.
link |
I kind of shifted over to other what I call
link |
NSDR, non-sleep deep-rest protocols, in favor of those.
link |
But many people like binaural beats
link |
and say that they benefit from them,
link |
especially while studying or learning.
link |
I think part of the reason for that
link |
relates to the ability to channel our focus
link |
when we have some background noise.
link |
And this is something I also get asked about a lot.
link |
Is it better to listen to music
link |
and have background noise when studying,
link |
or is it better to have complete silence?
link |
Well, there's actually a quite good literature on this
link |
as well, but not so much as it relates to binaural beats,
link |
but rather whether or not people are listening to music,
link |
so-called white noise, brown noise,
link |
believe it or not, there's white noise
link |
and there's brown noise, there's even pink noise,
link |
and how that impacts brain states
link |
that allow us to learn information better or not.
link |
So now I'd like to talk about white noise.
link |
And I want to be very clear that white noise has been shown
link |
to really enhance brain states for learning
link |
in certain individuals, in particular in adults.
link |
But white noise actually can have a detrimental effect
link |
on auditory learning and maybe even the development
link |
of the auditory system in very young children,
link |
in particular in infants.
link |
So first I'd like to talk about the beneficial effects
link |
of white noise on learning.
link |
There are some really excellent studies on this.
link |
The first one that I'd like to just highlight
link |
is one that's entitled Low-Intensity White Noise
link |
Improves Performance in Auditory Working Memory Task,
link |
This is a study that explored whether or not learning
link |
could be enhanced by playing white noise in the background.
link |
But the strength of the study is that they looked
link |
at some of the underlying neural circuitry
link |
and the activation of the neural circuitry in these people
link |
as they did the learning task.
link |
And what it essentially illustrates is that white noise,
link |
provided that white noise is of low enough intensity,
link |
meaning not super loud, right?
link |
Not imperceptible, so not so quiet that you can't hear it,
link |
but not super loud either.
link |
It actually could enhance learning to a significant degree.
link |
And this has been shown now for a huge number
link |
of different types of learning.
link |
There's a terrific article as well
link |
as in a somewhat obscure journal, at least obscure to me,
link |
which is the effects of noise exposure
link |
on cognitive performance and brain activity patterns.
link |
That's a study involving 54 subjects.
link |
They basically were evaluated for mental workload
link |
and attention under different levels of noise exposure,
link |
background noise, and different essentially loudness
link |
And the reason I like this study is that they looked
link |
at different levels of noise and types of noise,
link |
and they varied a number of different things
link |
as opposed to just doing a kind of two-condition,
link |
either white noise or no white noise type thing.
link |
And what they found, again, is that provided
link |
the white noise is not extremely loud,
link |
it could really enhance brain function
link |
for sake of learning any number
link |
of different kinds of information.
link |
Now, that's all great, but it really doesn't get
link |
to the kind of deeper guts of mechanism.
link |
And as a neuroscientist, what I really want to see
link |
is not just that something has an effect.
link |
That's always nice.
link |
It's always nice to see in a nice peer-reviewed study
link |
without any kind of commercial biases
link |
that there's an effect.
link |
Okay, binaural beats can enhance learning,
link |
or listening to white noise not too loud
link |
can enhance learning.
link |
But you really want to understand mechanism
link |
because once you understand mechanism,
link |
not only does it start to make sense,
link |
but you can also imagine ways
link |
in which you could develop better tools and protocols.
link |
So I was very relieved to find,
link |
or I should say excited to find this study
link |
published in the Journal of Cognitive Neuroscience.
link |
This is a 2014 paper.
link |
White noise improves learning by modulating activity
link |
in dopaminergic midbrain regions
link |
and the right superior temporal sulcus, okay?
link |
Now, I don't expect you to know
link |
what the right superior temporal sulcus is.
link |
I don't expect you to know
link |
what the dopamine midbrain region is,
link |
but if you're like me,
link |
you probably took highlighted notice
link |
of the word dopaminergic.
link |
Dopamine is a neuromodulator,
link |
meaning it's a chemical that's released in our brain
link |
and body, but mostly in our brain,
link |
that modulates, meaning controls the likelihood
link |
that certain brain areas will be active
link |
and other brain areas won't be active.
link |
And dopamine is associated with motivation.
link |
Dopamine is associated with craving.
link |
Motivation is associated with all sorts of different things,
link |
including movement.
link |
But what this study so nicely shows
link |
is that white noise can really enhance
link |
the activity of neurons
link |
in what's called the substantia nigra VTA.
link |
The substantia nigra VTA is a very rich source of dopamine,
link |
and that's because it's very chock-a-block
link |
full of dopamine neurons.
link |
It's an area of the brain
link |
that is perhaps the richest source of dopamine neurons.
link |
And you actually can see this brain region
link |
under the microscope.
link |
If you take a slice of brain or you look at a brain
link |
without even staining it for any proteins
link |
or dopamine or anything,
link |
it's two very dark regions
link |
at the kind of bottom of the brain.
link |
And the reason it's called substantia nigra,
link |
nigra meaning dark,
link |
is because the dopamine neurons actually make something
link |
and that makes those neurons dark.
link |
And so you've got these two regions down there
link |
that contain dopamine and can release dopamine
link |
and essentially activate other brain regions
link |
and activate our sense of motivation
link |
and activate our sense of desire
link |
to continue focusing and learning.
link |
But you can't just snap your fingers
link |
and make them release dopamine.
link |
You actually have to trigger dopamine release from them.
link |
Now, that trigger can be caused
link |
by being very excited about something
link |
or the fact that that thing gave you
link |
a lot of pleasure in the past
link |
or you're highly motivated by fear or desire.
link |
But what's so interesting to me is that it appears
link |
that white noise itself can raise
link |
the what we call the basal,
link |
the baseline levels of dopamine
link |
that are being released from this area,
link |
the substantia nigra.
link |
So now we're starting to get a more full picture
link |
of how particular sounds in our environment
link |
can increase learning.
link |
And that's in part, I believe,
link |
through the release of dopamine from substantia nigra.
link |
So I'm not trying to shift you away from binaural beats
link |
if that's your thing,
link |
but it does appear that turning on white noise
link |
at a low level, not too loud,
link |
you may say, well, how loud?
link |
And I'll tell you in a moment,
link |
but not too loud can allow you to learn better
link |
because of the ways that it's modulating
link |
your brain chemistry.
link |
So how loud or how soft should that white noise be
link |
Well, in these studies, it seemed that white noise
link |
that could be heard by the person,
link |
so it wasn't imperceptible to them,
link |
so it was loud enough that they could hear,
link |
but not so loud that they felt it was intrusive
link |
or irritating to them.
link |
So that's going to differ from person to person
link |
because people have different levels of auditory sensitivity.
link |
It's going to depend on age,
link |
going to depend on a number of different factors.
link |
So I can't tell you turn to level two
link |
on your volume controller.
link |
That's just not going to work.
link |
Also, I don't know how far you are
link |
from a given speaker in the room,
link |
or if you've got earphones in your head,
link |
or you've got speakers in the room,
link |
or if it's coming out of your computer.
link |
I don't know those things.
link |
So what you're going to have to do is adjust that white noise
link |
to a place where it's not interfering
link |
with your ability to focus,
link |
but rather it's enhancing your ability to focus.
link |
I think a good rule of thumb is going to be
link |
to put it probably on the lower third
link |
of any kind of volume dial,
link |
as opposed to in the upper third
link |
where it would really be blasting.
link |
And really blasting any noise, frankly, is not good,
link |
but that's especially not good,
link |
meaning it's especially bad, if you have headphones in.
link |
I do want to mention something about headphones
link |
before I talk about white noise in the developmental context
link |
and why it can be dangerous there.
link |
When you put headphones in your ears,
link |
it has this incredible effect of making the sounds
link |
like they come from inside your head,
link |
not from out in the room.
link |
And now that might seem like kind of a duh,
link |
but that's actually really amazing, right?
link |
Your brain assumes that the sounds are coming
link |
from inside your head,
link |
as opposed from the environment that you're in
link |
the moment you put headphones in.
link |
So if you're listening to an audio book,
link |
or maybe you're listening to this podcast with headphones,
link |
that's very different than when you're listening
link |
to something out in the room and there are other sounds,
link |
other sound waves,
link |
especially if you use these noise cancellation headphones.
link |
So if you're going to use white noise
link |
to enhance studying or learning of any kind,
link |
or this also could be for skill learning,
link |
motor skill learning while you're exercising,
link |
my suggestion would be that if you're using headphones
link |
to keep it quite low, right?
link |
This is an effect on the midbrain dopamine neurons.
link |
That's a background effect of raising the baseline
link |
of dopamine release.
link |
The way that dopamine neurons fires, they're always firing.
link |
Yours are firing right now, so are mine.
link |
When something exciting happens, they fire a lot.
link |
And when something disappointing happens,
link |
that firing, the release of dopamine
link |
goes down below baseline.
link |
What you're talking about here is raising
link |
your overall levels of attention and motivation,
link |
which translate to better learning,
link |
by just tickling those neurons a little bit,
link |
raising the baseline firing, okay?
link |
So you're not turning up the white noise
link |
to the point where you're feeling amazing.
link |
This isn't like turning on your favorite song.
link |
This is actually the opposite.
link |
This is about getting that baseline up just a bit, okay?
link |
So I recommend turning the volume up just a bit
link |
so that you can focus entirely on the tasks
link |
that you're trying to do.
link |
And of course, you've turned on white noise,
link |
so your attention might drift to that for a moment.
link |
Is it too loud? Is it too soft?
link |
If you can disappear into the work, so to speak,
link |
if your attention can disappear into the work,
link |
then that's probably sufficiently quiet.
link |
And for those of you that say,
link |
well, I like really loud music,
link |
and if I just blast the music,
link |
then I forget about the music.
link |
I don't suggest blasting music.
link |
And this is coming from somebody
link |
who really likes loud music.
link |
I grew up with kind of a loud, fast rules mentality.
link |
And if you don't know what loud, fast rules means,
link |
then I can't help you.
link |
But there's a time and a place, perhaps,
link |
to listen to music loud.
link |
But especially with headphones,
link |
you can trigger, excuse me, hearing loss quite rapidly.
link |
And unfortunately, because these hair cells
link |
that we talked about earlier,
link |
our central nervous system neurons,
link |
they do not regenerate.
link |
They do not come back.
link |
Now, along the lines of hearing loss,
link |
I should just say that the best way
link |
to blow out your hearing for good, to eliminate your hearing,
link |
is to have very loud sounds
link |
superimposed on a loud environment, okay?
link |
So loud environments can cause hearing loss over time.
link |
So if you work at a construction site clanging really loud,
link |
or if you work the soundboard in a club or something,
link |
you are headed towards hearing loss
link |
unless you protect your hearing
link |
with earplugs and headphones.
link |
Nowadays, some of the earplugs are very low profile,
link |
meaning you can't see them.
link |
So that's kind of nice so you're not like the,
link |
like when I was younger,
link |
you didn't want to be the dork
link |
to go to the concert with the earplugs,
link |
but turns out those dorks were smarter than everybody else
link |
because they're not the ones who are craning their neck
link |
to try and hear trivial things
link |
at the age of 30 or so
link |
because they blew out their hearing.
link |
So if you are working in a loud environment
link |
or you expose yourselves to a loud environment,
link |
you really want to avoid big inflections
link |
and sound above that.
link |
So loud environment plus fireworks,
link |
loud environment plus gunshot,
link |
loud environments plus very high frequency, intense sound.
link |
That's what we call the two-hip model.
link |
When you, this is also true for concussion
link |
that you can take a kind of a stimulus
link |
that normally would be below the threshold of injury.
link |
You add another stimulus at the same time
link |
that would be below the threshold of injury
link |
and then suddenly you killed the neurons.
link |
So I don't want to make people paranoid,
link |
but you do want to protect your hearing.
link |
It's no fun to lose your hearing.
link |
If you're going to use headphones
link |
and you feel like you want to crank it up all the way,
link |
just remember that the more that you can get
link |
out of a lower volume,
link |
meaning the longer that you can go listening to things
link |
the longer you'll be able to hear that music or that thing.
link |
So again, I'm not the hearing cop.
link |
That's not my job,
link |
but as somebody who's lost some of his high-frequency
link |
hearing, I can tell you it's not a pleasure.
link |
The old argument that it helps you not have to hear
link |
or listen to people that you don't want to listen to
link |
that doesn't really work.
link |
They just send you text messages instead.
link |
So what about white noise and hearing loss in development?
link |
You know, a lot of people with children
link |
have these kind of noise machines,
link |
like sound waves and things like that
link |
that help the kids sleep.
link |
And look, I think kids getting good sleep
link |
and parents getting good sleep is vital to physical
link |
and mental health and family health.
link |
So I certainly sympathize with those needs.
link |
However, there are data that indicate that white noise
link |
during development can be detrimental
link |
to the auditory system.
link |
I don't want to frighten any parents.
link |
If you played white noise to your kids,
link |
this doesn't mean that their auditory system
link |
or their speech patterns are going to be disrupted
link |
or that their interpretation of speech
link |
is going to be disrupted forever.
link |
But there are data published in the journal Science,
link |
and Science being one of the three apex journals,
link |
Science, Nature, Cell, the most stringent journals,
link |
data published in the journal Science some years ago,
link |
actually by a scientist who I know quite well.
link |
His name is Edward Chang.
link |
He's a medical doctor now.
link |
He's a neurosurgeon.
link |
He's actually the chair of neurosurgery at UCSF.
link |
And he runs a laboratory where they study auditory learning,
link |
neuroplasticity, et cetera.
link |
He and his mentor at the time, Mike Merzenich,
link |
published a paper showing that if young animals,
link |
and this wasn't animal models,
link |
were exposed to white noise, so shh,
link |
the very type of noise that I'm saying as a older person,
link |
and when I say older,
link |
I mean somebody who's in their late teens,
link |
early 20s and older,
link |
could benefit from listening to that at a low level
link |
in the background for sake of learning.
link |
Well, they exposed very young animals to this white noise.
link |
It actually disrupted the maps
link |
of the auditory world within the brain.
link |
And we haven't talked about these maps yet,
link |
but I want to take a moment and talk about them
link |
and explain this effect and what it might mean for you
link |
if you have kids or if you were exposed
link |
to a lot of white noise early on.
link |
So auditory information goes up into our cortex,
link |
into essentially the outside portion of our brain
link |
that's responsible for all of our higher level cognition,
link |
our planning, our decision-making, et cetera, creativity.
link |
And up there, we have what are called tonotopic maps.
link |
What's a tonotopic map?
link |
Well, remember the cochlea, how it's coiled,
link |
and at one end, it responds to high frequencies,
link |
and the other end, it responds to low frequencies?
link |
Sort of like a piano.
link |
The keys sound different as you extend down
link |
and up the piano keys,
link |
and it's organized in a very systematic way, right?
link |
It's not all intermixed high frequencies and low frequencies.
link |
It's organized in a very systematic way
link |
from one end to the other.
link |
Your visual system is in what's called a retinotopic map.
link |
So neighboring points in space off to my right,
link |
like my two fingers off to my right,
link |
are mapped to neighboring points in space in my brain.
link |
And the space right in front of me
link |
is mapped to a different location in my brain,
link |
but it's systematic.
link |
It's not salt and pepper.
link |
It goes from high to low, or from right to center to left.
link |
In the auditory system,
link |
we have what are called tonotopic maps,
link |
where frequency, high frequency to low frequency,
link |
and everything in between is organized
link |
in a very systematic way.
link |
Now, our experience of life from the time we're a baby
link |
until the time that we die is not systematic.
link |
We don't hear low frequencies at one part of the room
link |
or at one part of the day,
link |
and high frequencies at another part of the room
link |
and another part of the day.
link |
They're all intermixed.
link |
But if you remember, the cochlea separates them out
link |
just like a prism of light separates out
link |
the different wavelengths of light.
link |
The cochlea separates out the different frequencies.
link |
And the developing brain
link |
takes those separated out frequencies
link |
and learns this relationship between itself,
link |
meaning the child, and the outside world.
link |
White noise essentially contains no tonotopic information.
link |
The frequencies are all intermixed.
link |
Whereas when I speak, my voice has,
link |
now I'm getting technical,
link |
but it has what's called a certain envelope,
link |
meaning it has some low frequencies
link |
and some slightly high frequencies.
link |
I can make my voice higher,
link |
although I'm not very good at that.
link |
My voice starts to crack and I can make my voice lower,
link |
although not as low as Costello's snore.
link |
So it has an envelope, it has a container.
link |
White noise has no container.
link |
It's like all the colors of the rainbow spread out together,
link |
which is actually what you get when you get white light.
link |
White noise is analogous to white light.
link |
So one of the reasons why hearing a lot of white noise
link |
during development for long periods of time
link |
can be detrimental to the development of the auditory system
link |
is that these tonotopic maps don't form normally.
link |
At least they don't in experimental animals.
link |
Now, the reason I'm raising this is that many people I know,
link |
in particular friends who have small children,
link |
they say, I want to use a white noise machine while I sleep,
link |
but is it okay for my baby to use a white noise machine?
link |
And I consulted with various people, scientists about this,
link |
and they said, well, you know,
link |
the baby is also hearing the parents' voices
link |
and is hearing music and is hearing the dog bark,
link |
so it's not the only thing they're hearing.
link |
However, every single person that I consulted with said,
link |
but you know, there's neuroplasticity during sleep,
link |
that's when the kid is sleeping,
link |
and I don't know that you'd want to expose a child
link |
to white noise the entire night,
link |
because it might degrade that tonotopic map.
link |
It might not destroy it, it might not eliminate it,
link |
but it could make it a little less clear,
link |
like sort of taking the keys on the piano
link |
and taping a few of them together, right?
link |
So you've still got the highs and lows
link |
in the appropriate order and everything in between,
link |
but when you tape the keys together,
link |
you don't get the same fidelity,
link |
you don't get the same precision
link |
of the noise that comes out of that piano.
link |
So again, I don't want to scare anybody,
link |
but I would say if you are in a position
link |
to make the choice of either using white noise
link |
or something similar,
link |
pink noise is just a kind of variation,
link |
it's got a little bit more of a certain frequency,
link |
just like pink light has a little bit more
link |
of a certain wavelength than white light, kind of,
link |
if you are in a position to make choices
link |
about things to put in a young,
link |
especially very young child's sleeping environment,
link |
white noise might be something to consider avoiding.
link |
Again, I'm not telling you what to do,
link |
but it's something to perhaps consider avoiding.
link |
I don't think most pediatricians
link |
are going to be aware of these data,
link |
but if you talk to any auditory physiologist
link |
or an audiologist or somebody
link |
who studies auditory development,
link |
I'm fairly certain that they would have opinions about that.
link |
Now, whether or not their opinions agree with mine
link |
and these folks that I consulted with
link |
or not is a separate matter,
link |
I don't know because I don't know them,
link |
but it's something that I felt was important enough
link |
to cue you to, especially since I've highlighted,
link |
excuse me, the opposite effect is true in adulthood.
link |
Once your auditory system has formed,
link |
once it's established these tonotopic maps,
link |
then the presence of background white noise
link |
should not be a problem at all.
link |
In fact, it shouldn't be a problem at all
link |
because you're also not attending to it.
link |
The idea is that it's playing at a low enough volume
link |
that you kind of forget it in the background
link |
and that it's supporting learning
link |
by bringing your brain into a heightened state of alertness
link |
and especially this heightened state of dopamine,
link |
dopaminergic activation of the brain,
link |
which will make it easier to learn faster
link |
and easier to learn the information.
link |
So now I want to talk about auditory learning
link |
and actually how you can get better
link |
at learning information that you hear,
link |
not just information that you see on a page
link |
or motor skill learning.
link |
There are a lot of reasons to want to do this.
link |
A lot of classroom teaching,
link |
whether or not it's by Zoom or in person,
link |
is auditory in nature.
link |
Not everything is necessarily written down for us.
link |
It's also good to get better at listening, or so I'm told.
link |
So there's a phenomenon called the cocktail party effect.
link |
Now, even if you've never been to a cocktail party,
link |
you've experienced and participated
link |
in what's called the cocktail party effect.
link |
The cocktail party effect is where you are in an environment
link |
that's rich with sound,
link |
many sound waves coming from many different sources,
link |
many different things.
link |
So in a city, in a classroom,
link |
in a car that contains people having various conversations,
link |
you somehow need to be able to attend
link |
to specific components of those sound waves,
link |
meaning you need to hear certain people and not others.
link |
The reason it's called the cocktail party effect
link |
is that you, and meaning your brain,
link |
are exquisitely good at creating a cone
link |
of auditory attention, a narrow band of attention
link |
with which you can extract the information you care about
link |
and wipe away or erase all the rest.
link |
Now, this takes work.
link |
It takes attention.
link |
One of the reasons why you might come home
link |
from a loud gathering, maybe a stadium, a sports event,
link |
or a cocktail party for that matter,
link |
and feel just exhausted is because if you were listening
link |
to conversations there or trying to listen
link |
to those conversations while watching the game
link |
and people moving past you and hearing all this noise,
link |
clinking of glasses, et cetera,
link |
it takes attentional effort,
link |
and the brain uses up a lot of energy just at rest,
link |
but it uses up even more energy
link |
when you are paying strong attention to something,
link |
literally caloric energy,
link |
burning up things like glucose, et cetera.
link |
Even if you're ketogenic, it's burning up energy.
link |
So the cocktail party effect has been studied extensively
link |
in the field of neuroscience,
link |
and we now know at a mechanistic level
link |
how one accomplishes this feat of attending to certain sounds
link |
despite the fact that we are being bombarded
link |
with all sorts of other sounds.
link |
So there are a couple of ways that we do this.
link |
First of all, much as with our visual system,
link |
we can expand or contract our visual field of view.
link |
So we can go from panoramic vision,
link |
see the entire scene that we are in by dilating our gaze.
link |
I've talked a lot about this on this podcast and elsewhere.
link |
We can, for instance, keep our head and eyes stationary
link |
or mostly stationary.
link |
You don't have to be rigid about it,
link |
and you can expand your field of view
link |
so you can see the walls and ceiling and floor.
link |
You can see yourself in the environment.
link |
That's panoramic view.
link |
It's what you would accomplish without having to try at all
link |
if you went to a horizon, for instance.
link |
Or we can contract our field of view.
link |
I can bring my focus to a particular location,
link |
what we call a vergence point, directly in front of me.
link |
Now I'm pointing at the camera directly in front of me.
link |
Okay, we can do that.
link |
We can expand and contract our visual field of view.
link |
Well, we can expand and contract our auditory field of view,
link |
so to speak, or our auditory window.
link |
You can try this next time you are in an environment
link |
that's rich with noise, meaning lots of different sounds.
link |
You can just tune out all the noise to a background chatter.
link |
You kind of just, you try not focus
link |
on any one particular sound,
link |
and you get the background kind of chatter of noise.
link |
And you'll find that it's actually very relaxing
link |
in comparison to trying to listen to somebody
link |
at a cocktail party and you're shouting back and forth.
link |
Now, if you're very, very interested in that person
link |
or getting to know them better or what they're telling you
link |
or some combination of those things,
link |
then you'll be very motivated to do it,
link |
but nonetheless, it requires energy and effort and attention.
link |
How do we do this?
link |
Well, it's actually quite simple,
link |
or at least it's simple in essence,
link |
although the underlying mechanisms are complex.
link |
Here, I have to credit the laboratory
link |
of a guy named Mike Wehr, W-E-H-R,
link |
up at the University of Oregon,
link |
who essentially figured out that we are able
link |
to accomplish this extraction of particular sounds.
link |
We can really hear one person or a small number of people
link |
amidst a huge background of chatter
link |
because we pay attention to the onset of words,
link |
but also to the offset of words.
link |
Now, the way to visualize this is if the background noise
link |
is just like a bunch of waves of noise,
link |
it's literally just sound waves coming every frequency,
link |
low frequency, high frequency, glasses clinking together.
link |
If you're at a game, people are shouting,
link |
people are talking on their phone.
link |
There's the crack of the ball if somebody actually manages
link |
to hit the ball, the announcer, et cetera.
link |
But whatever we're paying attention to,
link |
we set up a cone of auditory attention,
link |
a kind of a tunnel of auditory attention
link |
where we are listening, although we don't realize it,
link |
we are listening for the onset and the offset of those words.
link |
Now, this is powerful for a couple of reasons.
link |
First of all, it's a call to arms, so to speak,
link |
to disengage your auditory system
link |
when you don't need to focus your attention
link |
on something particular.
link |
So if you are somebody, you're coming home from work,
link |
you've had a very long day,
link |
and you're trying to make out a particular conversation
link |
on background noise,
link |
you might consider just not having that conversation,
link |
just letting your auditory landscape be very broad,
link |
almost like panoramic vision.
link |
If you're trying to learn
link |
how to extract sound information,
link |
it could be notes of music, it could be scales of music,
link |
it could be words spoken by somebody else.
link |
Maybe somebody is telling you what you need to say
link |
for a particular speech,
link |
or the information that you need to learn
link |
for a particular topic, and they're telling it to you.
link |
Deliberately paying attention both to the onset
link |
and to the offset of those words can be beneficial
link |
because it is exactly the way that the auditory system
link |
likes to bring in information.
link |
So one of the more common phenomenon
link |
that I think we all experience
link |
is you go to a party, or you meet somebody new,
link |
and you say, hi, I would say, hi, I'm Andrew,
link |
and they'd say, hi, I'm Jeff, for instance,
link |
great to meet you.
link |
And then a minute later, I can't remember the guy's name.
link |
Now, is it because I don't care what his name is?
link |
No, somehow the presence
link |
of other auditory information interfered.
link |
It's not that my mind was necessarily someplace else,
link |
it's that the signal to noise, as we say, wasn't high enough.
link |
Somehow the way he said it or the way it landed on my ears,
link |
which is really all that matters, right,
link |
when it comes down to learning,
link |
is such that it just didn't achieve
link |
high enough signal to noise.
link |
The noise was too high or the signal was too low
link |
or some combination of those.
link |
So the next time you ask somebody's name,
link |
remember, listen to the onset of what they say
link |
So it would be paying attention to the j in Jeff,
link |
and it would be paying attention to the th in F, in Jeff,
link |
excuse me, all right?
link |
And chances are you'll be able to remember that name.
link |
Now, I don't know if people who are super learners of names
link |
do this naturally or not.
link |
I don't have access to their brains.
link |
I don't think they're going to give me access
link |
to their brains either,
link |
but it's a very interesting way to take the natural biology
link |
of auditory attention and learning
link |
and apply it to scenarios where you're trying to remember
link |
either people's names or specific information.
link |
Now, I do acknowledge that trying to learn every word
link |
in a sentence by paying attention to its onset and offset
link |
could actually be kind of disruptive
link |
to the learning process.
link |
So this would be more for specific attention.
link |
Like you're asking directions in a city and somebody says,
link |
okay, you say you're lost, and they say, okay,
link |
you're going to go two blocks down,
link |
you're going to turn left,
link |
and then you're going to see a landmark on your right,
link |
and then you're going to go in the third door on your left.
link |
That's a lot of information, at least for me, okay?
link |
So the way you would want to listen to that is
link |
you're going to go down the road.
link |
See, I already forgot.
link |
You're going to go left, and you're just going to program,
link |
and instead of just hearing the word left,
link |
you're going to think the L at the front of left and the T.
link |
You're going to left, okay?
link |
And then, so you're coding in specific words,
link |
and what this does is this kind of hijacks
link |
these naturally occurring attention mechanisms
link |
that the auditory system likes to use.
link |
It's a little bit of data that for auditory encoding,
link |
this kind of thing can be beneficial.
link |
There are a lot of data that attention
link |
for auditory coding is beneficial.
link |
There are a little bit of data showing
link |
that deliberately encoding auditory information this way,
link |
meaning trying to learn auditory information this way,
link |
can be beneficial or can accelerate learning.
link |
And some of these features of what I'm describing here
link |
map onto some of the work of Mike Merzenich and others
link |
that have been designed to try and overcome things
link |
like stutter and to treat various forms
link |
of auditory learning disorders.
link |
But more importantly, and perhaps more powerful,
link |
is the work of Mike Merzenich
link |
that was done with his then graduate student,
link |
Greg Recanzone, that showed that
link |
using the attentional system,
link |
we can actually learn much faster
link |
and we can actually activate neuroplasticity
link |
in the adult brain, something that's very challenging to do,
link |
and that the auditory system is one of the main ways
link |
in which we can access neuroplasticity more broadly.
link |
So I just want to take a couple of minutes
link |
and describe the work of Recanzone and Merzenich
link |
because it's absolutely fantastic and fascinating.
link |
What they did is they had subjects
link |
try to learn auditory information,
link |
except that they told them to pay attention
link |
to particular frequencies.
link |
So now you know what frequencies are,
link |
so essentially high-pitched sounds or low-pitched sounds.
link |
What they found was just passively listening
link |
to a bunch of stuff does not allow the brain to change
link |
and for that stuff to be remembered at all.
link |
That's not a surprise.
link |
We've all experienced the phenomenon of having someone talk
link |
and we see their mouth moving and we're like,
link |
yeah, this is really important, this is really important,
link |
we're listening, we're trying to listen,
link |
and then they walk away and we think,
link |
I didn't get any of that.
link |
And you wonder whether or not it was them,
link |
maybe this is happening to you right now,
link |
you wonder whether or not it was you,
link |
you wonder whether or not you have trouble with learning
link |
or you have attention deficit,
link |
it could be any number of different things.
link |
But what Recanzone and Merzenich discovered
link |
was that if you instruct subjects to listen
link |
for particular cues within speech or within sounds,
link |
that not only can you learn those things more quickly,
link |
but that you can remap these tonotopic maps in the cortex
link |
that I referred to earlier,
link |
you actually get changes in the neural architecture,
link |
the neural circuitry in the brain,
link |
and this can occur not only very rapidly,
link |
but they can occur in the adult brain,
link |
which prior to their work
link |
was not thought to be amenable to change.
link |
It was long thought that neuroplasticity
link |
could only occur in the developing brain,
link |
but the work of Recanzone and Merzenich
link |
in the auditory system actually was some of the first
link |
that really opened up everybody's eyes and ears
link |
to the idea that the brain can change in adulthood.
link |
So here's how this sort of process would work
link |
and how you might apply it.
link |
If you are trying to learn music
link |
or you're trying to learn information
link |
that you're going to then recite,
link |
you can decide to highlight certain words
link |
or certain frequencies of sound
link |
or certain scales or certain keys on the piano
link |
and to only focus on those for certain learning bouts, okay?
link |
So I'll give an example that's sort of real time for me,
link |
meaning it's happening right now.
link |
I know generally what I want to say when I arrive here.
link |
I even know specifically certain things
link |
that I want to make sure get across to you,
link |
but I don't think about every single word
link |
that I'm going to say and the precise order
link |
in which I'm going to say those things.
link |
That would be actually very disruptive
link |
because it wouldn't match my normal patterns of speech
link |
and you'd probably think I was sounding rather robotic
link |
if I were to do that.
link |
So one way that we can remember information is
link |
as we write out, for instance, something that we want to say,
link |
we can highlight particular words.
link |
We can underline those.
link |
If we're listening to somebody
link |
and they are telling us information,
link |
we can decide just to highlight particular words
link |
that they said to us and write those down.
link |
Now, of course, we're listening to all the information,
link |
but the work of Reckinzone and Murzenich
link |
and the work of others, in addition to them,
link |
his former student or former postdoc, I don't know which,
link |
Michael Kilgard, who's now got his own lab down in Texas,
link |
or others, have shown that the queuing of attention
link |
to particular features of speech,
link |
particular components of speech,
link |
the way in which it increases our level of attention overall
link |
allows us to capture more of the information overall.
link |
And so I don't want this to be abstract at all.
link |
What this means is when you're listening,
link |
you don't have to listen to every word.
link |
You're already listening to every word.
link |
All the information's coming in through your ears.
link |
What you're trying to extract is particular things
link |
or themes within the content.
link |
So maybe you decide, if you're listening to me,
link |
that you're only going to listen to the word tools,
link |
or you're only going to listen
link |
to when my voice kind of goes above background.
link |
You get to decide what you decide to listen to or not.
link |
And what you decide to focus on
link |
isn't necessarily as important
link |
as the fact that you're focusing.
link |
So I hope that's clear.
link |
The auditory system does this all the time
link |
with the cocktail party effect.
link |
What I'm talking about is exporting certain elements
link |
of the mechanisms of the cocktail party effect,
link |
paying attention to the onset and offset of words,
link |
or particular notes within music, or particular scales,
link |
or you can make it even broader
link |
and particular motifs of music,
link |
or particular sentences of words, or particular phrases.
link |
And in doing that,
link |
you extract more of the information overall,
link |
even though you're not paying attention
link |
to all the information at once.
link |
Now I'd like to talk about a phenomenon
link |
that you've all experienced before,
link |
which is called Doppler.
link |
So the Doppler effect is the way that we experience sound
link |
when the thing that's making that sound is moving.
link |
The simplest way to explain this
link |
is to translate the sound into the visual world once again.
link |
So if you've ever seen a duck or a goose
link |
sitting in a pond or a lake,
link |
and it's kind of bobbing up and down,
link |
what you'll notice is that the ripples of water
link |
that extend out from that duck or goose
link |
are fairly regularly spaced in all directions.
link |
And that's because that duck or goose is stationary.
link |
It's moving up and down,
link |
but it's not moving forward or backward or to the side.
link |
Now, if that duck or goose were to swim forward
link |
by paddling its little webbed feet under the surface,
link |
you would immediately notice that the ripples of water
link |
that are close to and in front of that duck or goose
link |
would be closer together than the ones that trailed it
link |
And that is essentially what happens with sound as well.
link |
With the Doppler effect,
link |
we experience sounds that are closer to us
link |
at higher frequency, the ripples are closer together,
link |
and sounds that are further away at lower frequency,
link |
especially when they're moving past us.
link |
So if you've ever, for instance,
link |
heard a siren in the distance,
link |
nuh, nuh, nuh, nuh, nuh, nuh, nuh, nuh, nuh, nuh, nuh,
link |
that's essentially my rendition of a siren,
link |
I don't know what ambulance or police or what,
link |
passing you on a street.
link |
That is the Doppler effect.
link |
The Doppler effect is one of the main ways
link |
that we make out the direction that things are arriving from
link |
and their speeds and trajectories.
link |
And we get very good from a very young age
link |
at discerning what direction things are arriving from
link |
and the direction that they are going to pass us in.
link |
And the Doppler effect has probably saved your life
link |
In this way, you just don't realize it
link |
because you'll step off the curb
link |
or you're driving your car and you pull to the side
link |
so that the ambulance or fire truck can go by
link |
because you heard that siren off in the distance.
link |
And then you pull away from the curb
link |
and you get back on the road,
link |
in part because you don't see it any longer,
link |
but also you don't hear any other sirens in the distance.
link |
Now, some animals such as bats are exquisitely good
link |
at navigating their environments according to sound.
link |
Now, we've all heard that bats don't see,
link |
that's actually not true, they actually have vision,
link |
but they just rely more heavily on their auditory system.
link |
And the way that bats navigate in the dark
link |
and the way that bats navigate using sound
link |
is through Doppler.
link |
Now, they don't simply listen to whether or not
link |
things are coming at them or moving away from them
link |
and pay attention to Doppler
link |
like the siren example I gave for you.
link |
What they do is they generate their own sounds.
link |
So a bat, as it flies around, is sending out clicks.
link |
I think that's my best bat sound, or maybe it is.
link |
And they're clicking, they're actually propelling sound out
link |
at a particular frequency that they know.
link |
Now, whether or not they're conscious of it, I don't know.
link |
I've never asked them.
link |
And if I did ask them, I don't think they could answer.
link |
And if they could answer,
link |
they couldn't answer in a language that I could understand.
link |
But the bat is essentially flying around,
link |
sending out sound waves,
link |
pinging its environment with sound waves
link |
of a particular frequency.
link |
And then depending on the frequency of sound waves
link |
that come back, they know if they're getting closer
link |
to an object or further away from it.
link |
So if they send out sounds at a frequency of,
link |
this was much slower than it would actually occur,
link |
but let's say one every half second,
link |
and it's coming back even faster,
link |
then they know they're getting closer
link |
because of the Doppler effect.
link |
And if it comes back more slowly,
link |
they know that there's nothing in front of them.
link |
So the bat is essentially navigating its world
link |
by creating these auras of sound
link |
that bounce back onto them from the various objects,
link |
trees, et cetera, buildings, and people.
link |
It's kind of eerie to think about,
link |
but yes, they see you, they experience you with their sound,
link |
they sense you, and they're using Doppler to accomplish it.
link |
Now I'd like to talk about ringing in the ears.
link |
This is something that I get asked about a lot.
link |
And speaking of signal to noise,
link |
I don't know if I get asked about it a lot
link |
because many people suffer from ringing in their ears
link |
or because the people who suffer from ringing in their ears
link |
suffer so much that they are more prone to ask.
link |
So it could be a sampling bias, I don't know,
link |
but I've been asked enough times,
link |
and some of the experiences of discomfort
link |
that people have expressed
link |
about having this ringing of the ears
link |
really motivate me to go deep into this literature.
link |
So the ringing of the ears that one experiences
link |
is called tinnitus, not tinnitus, but tinnitus.
link |
And tinnitus can vary in intensity
link |
and it can vary according to stress levels.
link |
It can vary across the lifespan or even time of day.
link |
So it's very subject to kind of background effects
link |
and contextual effects.
link |
So I think we all know that we should do our best
link |
to maximize healthy sleep.
link |
We did a number of episodes on that.
link |
Essentially the first four episodes
link |
of the Huberman Lab Podcast were all about sleep
link |
and how to get better sleep.
link |
We all know that we should try and limit our stress,
link |
and we had an episode about stress
link |
and ways to mitigate stress as well.
link |
However, there are people, it seems,
link |
that are suffering from tinnitus
link |
for which stress or lack of sleep
link |
just can't explain the presence of the tinnitus.
link |
Tinnitus can be caused by disruption to these hair cells
link |
that we talked about earlier or damage to the hair cells.
link |
So that's another reason why,
link |
even if you have good hearing now,
link |
that you want to protect that hearing
link |
and really avoid putting yourself
link |
into these kind of two-hit environments,
link |
environments where there's a lot of background noise
link |
and then you add another really loud auditory stimulus.
link |
This also can happen at different times, I should mention.
link |
If you go to a concert or you listen to loud music
link |
with your headphones and then you go to a concert
link |
or you go into a very loud work environment,
link |
the hair cells can still be vulnerable.
link |
And once those hair cells are knocked out,
link |
currently we don't have the technology to put them back,
link |
although many groups,
link |
including some excellent groups at Stanford and elsewhere,
link |
too, of course, are working on ways
link |
to replenish those hair cells and restore hearing.
link |
There are treatments for tinnitus
link |
that involve taking certain substances.
link |
There are medications for tinnitus.
link |
In the non-prescription landscape,
link |
which is typically what we discuss on this podcast
link |
when we discuss taking anything,
link |
there are essentially four compounds
link |
for which there are quality peer-reviewed data
link |
where there does not appear to be any overt commercial bias,
link |
meaning that nothing's reported in the papers
link |
as funding from a particular company.
link |
And those are melatonin, ginkgo bilboa, zinc, and magnesium.
link |
Now, I've talked about melatonin before.
link |
I'm personally not a fan of melatonin as a sleep aid,
link |
but there are four studies.
link |
First one entitled,
link |
the effects of melatonin on tinnitus and sleep.
link |
Second one, treatment of central and sensory neural tinnitus
link |
with orally administered melatonin.
link |
And then the title goes on much longer,
link |
but it's a randomized study.
link |
I'm not going to read out all of these.
link |
Melatonin, can it stop the ringing?
link |
Which is an interesting article, double-blinded study.
link |
And the effects of melatonin on tinnitus.
link |
Each one of these studies has anywhere from 30
link |
to more than 100 subjects, in one case, 102 subjects,
link |
both genders as they list them out.
link |
Typically it's listed as sex, not gender in studies.
link |
So it should say both sexes, but nonetheless.
link |
An age range anywhere from 30 years old
link |
all the way up to 65 plus.
link |
I didn't see any studies of people younger than 30.
link |
All three focused on melatonin,
link |
not surprisingly because of the titles.
link |
Looking at a range of dosages
link |
anywhere from three milligrams per day,
link |
which is sort of typical of many supplements for melatonin,
link |
still much higher than one would manufacture
link |
endogenously through your own pineal gland.
link |
But three milligrams in these studies
link |
for a duration of anywhere from 30 days
link |
to much longer in some cases, six months.
link |
And all four of these studies found modest,
link |
yet still statistically significant effects
link |
of taking melatonin by mouth,
link |
so it's orally administered melatonin,
link |
in reducing the severity of tinnitus.
link |
So that's compelling, at least to me.
link |
It doesn't sound like a cure.
link |
And of course, as always, I'm not a physician.
link |
I'm a scientist, so I don't prescribe anything.
link |
I only profess things.
link |
I report to you the science.
link |
You have to decide if melatonin is right for you,
link |
if you have tinnitus.
link |
And certainly I say that both to protect myself,
link |
but also protect you.
link |
You're responsible for your health and wellbeing.
link |
And I'm not telling anyone to run out
link |
and start taking melatonin for tinnitus,
link |
but it does seem that it can have some effects
link |
in reducing its symptoms.
link |
Ginkgo boa boa is an interesting compound.
link |
It's been prescribed for or recommended for many,
link |
many things, but there are a few studies,
link |
again, double-blinded studies lasting one to six months.
link |
Any one that has an impressive number of subjects,
link |
978 subjects ranging from age 18 all the way up to 65,
link |
so on and so forth,
link |
that show not huge effects of ginkgo,
link |
but as they quote,
link |
"'limited evidence' suggests that if tinnitus
link |
is a side effect of something else,
link |
in particular cognitive decline,"
link |
so age-related tinnitus might be helped by ginkgo boa boa.
link |
I won't go through all the details of the zinc studies,
link |
but it seems that zinc supplementation at higher levels
link |
than are typical of most people's intake,
link |
so 50 milligrams per day,
link |
do appear to be able to reduce subjective symptoms
link |
of tinnitus in most of the people
link |
that took the supplemented zinc.
link |
There aren't a lot of studies on that,
link |
so I could only find one double-blinded study.
link |
It lasted anywhere from one to six months, 41 subjects,
link |
both genders listed out again here, 45 to 64,
link |
and they saw a decrease in the severity
link |
of tinnitus symptoms with 50 milligrams
link |
of elemental zinc supplementation.
link |
And then last but not least is the magnesium study.
link |
Again, only a single study.
link |
It's a phase II study
link |
looking at a fairly limited number of subjects,
link |
so only 19 subjects,
link |
taking 532 milligrams of elemental magnesium.
link |
For those of you that take magnesium,
link |
there's magnesium and elemental magnesium,
link |
and it's always translated on the bottle,
link |
but it was associated with a lessening of symptoms
link |
related to tinnitus.
link |
So for you tinnitus sufferers out there,
link |
you may already be aware of this.
link |
You may already be taking these things
link |
and had no positive effects,
link |
meaning they didn't help, maybe not.
link |
I hope that you'll at least consider these,
link |
talk to your doctor about them.
link |
I do realize that tinnitus is extremely disruptive.
link |
I can't say I empathize
link |
because I don't from a place of experience, that is,
link |
because I don't have tinnitus,
link |
but for those of you that don't, including myself,
link |
you can imagine that hearing sounds
link |
of things that aren't there
link |
and the ringing in one's ears can be very disruptive,
link |
and I think would be very disruptive,
link |
and it explains why people with tinnitus reach out so often
link |
with questions about how to alleviate that,
link |
and I hope this information was useful to you.
link |
I'd like to now talk about balance and our sense of balance,
link |
which is controlled by, believe it or not,
link |
our ears and things in our ears,
link |
as well as by our brain and elements of our spinal cord.
link |
But before I do that, I want to ask you another question,
link |
or I would rather, I'd like to ask you
link |
to ask yourself a question and answer it,
link |
which is how big are your ears?
link |
It turns out that the ears grow our entire life.
link |
In the early stage of our life, they grow more slowly,
link |
and then as we age, they grow more quickly.
link |
You may have noticed if you have family members
link |
who are well into their 70s and 80s,
link |
and if you're fortunate into their 90s
link |
and maybe even hundreds is that the ears
link |
of some of these individuals get very, very big
link |
relative to their previous ear sizes.
link |
It turns out that biological age
link |
can actually be measured according to ear size.
link |
Now, you have to take a few measurements,
link |
but believe it or not, there is a formula
link |
in the scientific literature.
link |
If you know your ear circumference,
link |
so the distance around your ear, ears, plural,
link |
presumably you have two, most people do, in millimeters,
link |
so you're going to take the circumference of your ears
link |
in millimeters, how would you do this, right?
link |
How would you do this?
link |
Maybe you take a string and you put it around your ear
link |
and then you measure the string.
link |
That's probably going to be easier
link |
than marching around your ear or somebody else's ear
link |
with a ruler and measuring in millimeters.
link |
So what's your ear circumference?
link |
On the outside, don't go in on the divot or anything,
link |
you're just going around as if you were going to trace
link |
the closest fitting oval, assuming your ears are oval,
link |
closest fitting oval that matches your ear circumference.
link |
Take that number in millimeters, subtract from it.
link |
Oh, excuse me, I should do this correctly.
link |
Do that for both ears, add them together,
link |
add those numbers together, divide by two,
link |
get the average for your two ears,
link |
get your average ear circumference
link |
from across your two ears,
link |
then take that number in millimeters, subtract 88.1,
link |
and then whatever value that is, multiply it times 1.96,
link |
and that will tell you your biological age.
link |
Now, why in the world would this be accurate?
link |
Well, as we age, there are changes in a number
link |
of different biological pathways.
link |
One of those pathways is the pathways related
link |
to collagen synthesis.
link |
So not only are our ears growing,
link |
but our noses are growing too.
link |
My nose seems to be growing a lot, but then again,
link |
I did sports where I would get my nose broken,
link |
something I don't recommend.
link |
So I always point out, you don't get a nose like mine
link |
doing yoga, but nonetheless, my nose is still growing
link |
and my ears are still growing, and I suspect as I get older,
link |
if I have the good fortune of living into my 80s and 90s,
link |
my ears are going to continue to grow.
link |
A comparison between chronological age
link |
and biological age is something that's
link |
of really deep interest these days,
link |
and the work of David Sinclair
link |
at Harvard Medical School and others,
link |
so-called Horvath clocks that people have developed,
link |
have tapped into how the epigenome and the genome
link |
can give us some insight into our biological age
link |
and how that compares to our chronological age.
link |
Most of us know our chronological age
link |
because we know when we were born,
link |
and we know where we are relative to that now.
link |
But you can start to make a little chart, if you like,
link |
about your rates of ear growth.
link |
Your rates of ear growth actually correlate pretty well
link |
with your rates of biological progression
link |
through this thing that we call life.
link |
So it's not something that we think about too often,
link |
but just like our DNA and our epigenome
link |
and some other markers of metabolic health
link |
and hormone health relate to our age,
link |
so does our collagen synthesis,
link |
and one of the places that shows up the most
link |
is in these two little goodies on the sides of our heads,
link |
which are our ears.
link |
So even though it's a little bit of a bizarre metric,
link |
it makes perfect sense in the biological context.
link |
So let's talk about balance
link |
and how to get better at balancing.
link |
The reason why we're talking about balance
link |
and how to get better at balancing
link |
in the episode about hearing is that all the goodies
link |
that are going to allow you to do that are in your ears.
link |
And they're also in your brain,
link |
but they're mostly in your ears.
link |
So as you recall from the beginning of this episode,
link |
you have two cochlea, cochleas,
link |
that are one on each side of your head,
link |
and that's a little spiral snail-shaped thing
link |
that converts sound waves into electrical signals
link |
that the rest of your brain can understand.
link |
Right next to those,
link |
you have what are called semicircular canals.
link |
The semicircular canals can be best visualized
link |
as thinking about three hula hoops with marbles in them.
link |
So imagine that you have a hula hoop
link |
and it's not filled with marbles all the way around,
link |
it's just got some marbles down there at the base.
link |
Okay, so if you were to move that hula hoop around,
link |
the marbles will move around.
link |
Shoo, shoo, shoo, okay?
link |
You've got three of those,
link |
and each one of those hula hoops has these marbles
link |
that can move around.
link |
One of those hula hoops is positioned vertically
link |
with respect to gravity.
link |
So it's basically parallel to your nose.
link |
It's like this, if you're watching on a video,
link |
but basically it's upright.
link |
Another one of those hula hoops
link |
is basically at a 90-degree angle to your nose.
link |
It's basically parallel to the floor
link |
if you're standing upright now, if you're seated, okay?
link |
And the other one is kind of tilted
link |
about 45 degrees in between those.
link |
Now, why is the system there?
link |
Well, those marbles within each one of those hula hoops
link |
can move around, but they'll only move around
link |
if your head moves in a particular way.
link |
And there are three planes or three ways
link |
that your head can move.
link |
Your head can move up and down, like I'm nodding right now.
link |
So that's called pitch.
link |
It's pitching forward or pitching back, okay?
link |
So it's a nod, up and down.
link |
Or I can shake my head no, side to side.
link |
That's called yaw.
link |
You pilots will be very familiar with this, yaw.
link |
And then there's roll, tilting the head from side to side,
link |
the way that a cute puppy might look at you
link |
from side to side, okay?
link |
Where if somebody doesn't really understand
link |
or believe what you're saying,
link |
they might tilt their head, very common phenomenon.
link |
I mean, nobody does that to me,
link |
but they do that to each other.
link |
So pitch, yaw, and roll are the movements of the head
link |
in each of the three major planes of motion, as we say.
link |
And each one of those causes those marbles to move
link |
in one or two of the various hula hoops, okay?
link |
So if I move my head up and down when I nod,
link |
one of those hula hoops, literally right now,
link |
the marbles are moving back and forth.
link |
They aren't actually marbles, by the way.
link |
These are little, kind of like little stones, basically,
link |
little calcium-like deposits.
link |
And when they roll back and forth,
link |
they deflect little hairs, little hair cells
link |
that aren't like the hair cells
link |
that we use for measuring sound waves.
link |
They're not too different, but they are different from them.
link |
Not like the hairs on our heads,
link |
but they're basically rolling past these little hair cells
link |
and causing them to deflect.
link |
And when they deflect downward, the neurons,
link |
because hair cells are neurons,
link |
send information up to the brain.
link |
So if I move my head like this,
link |
there's a physical movement of these little stones
link |
in this hula hoop, as I'm referring to it,
link |
but they deflect these hairs, send those hairs,
link |
which are neurons, those hair cells,
link |
send information off to the brain.
link |
If I move my head from side to side,
link |
different little stones move.
link |
If I roll my head, different stones move.
link |
This is an exquisite system that exists
link |
in all animals that have a jaw.
link |
So any fish that has a jaw has this system.
link |
A puppy has this system.
link |
Any animal that has a jaw has this so-called balance system,
link |
which we call the vestibular system.
link |
One of the more important things to know
link |
about the vestibular, the balance system,
link |
is that it works together with the visual system.
link |
Let's say I hear something off to my left
link |
and I swing my head over to the left to see what it is.
link |
There are two sources of information
link |
about where my head is relative to my body,
link |
and I need to know that.
link |
First of all, when I quickly move my head to the side,
link |
those little stones, as I'm referring to them,
link |
I realize they're not actually stones,
link |
but as I'm referring to them,
link |
they quickly activate those hair cells
link |
in that one semicircular canal
link |
and send a signal off to my brain
link |
that my head just moved to the side like this.
link |
Not that it went like this and pitched back,
link |
or not that it tilted, but it just moved to the side.
link |
But also, visual information slid past my field of view.
link |
I didn't have to think about it,
link |
but just slid past my field of view.
link |
And when those two signals combine,
link |
my eyes then lock to a particular location.
link |
Now, if this is at all complicated,
link |
you can actually uncouple these things.
link |
It's very easy to do.
link |
You can do this right now.
link |
In fact, I'd like you to do this experiment
link |
if you're not already doing something else
link |
that requires your attention,
link |
and certainly don't do this if you're driving.
link |
You're going to sit down
link |
and you're going to move your head to the left very slowly
link |
with your eyes open.
link |
So you're going to move it very, very slowly.
link |
The whole thing should take about five, six,
link |
maybe even 10 seconds to complete.
link |
Okay, I just did it.
link |
Now I'm going to do it very quickly.
link |
I'd like you to do it very quickly as well.
link |
Now do it slowly again.
link |
Okay, what you probably noticed
link |
is that it's very uncomfortable to do it slowly,
link |
but you can do it very quickly
link |
without much discomfort at all.
link |
You just move your head to the side.
link |
The reason is when you move your head very slowly,
link |
those little stones at the base of that hula hoop,
link |
they don't get enough momentum to move.
link |
So you're actually not generating this signal to the brain
link |
that your head is moving.
link |
And what you'll notice is that your eyes have to go boom,
link |
boom, boom, jumping over step by step.
link |
Whereas if you move your head really quickly,
link |
the signal gets off to your brain and your eyes just go,
link |
boom, right to the location you want to look at.
link |
So moving your body slowly is actually very disruptive
link |
to the vestibular system.
link |
And it's very disruptive to your visual system.
link |
Now, if you've ever had the misfortune of being on a boat
link |
and you're going through big oscillations on the boat,
link |
for those of you folks that get seasick,
link |
this can actually make certain people seasick
link |
just to hear about it.
link |
That was big oscillations going up and down
link |
Those are very disruptive.
link |
We'll talk about nausea in a minute
link |
and how to offset that kind of nausea.
link |
I get pretty seasick,
link |
but there are ways that you can deal with this.
link |
But this is incredible because what it means
link |
is it's a purely physical system of these little stones
link |
rolling around in there
link |
and directing where your eyes should go, okay?
link |
So you can do this also just by looking up.
link |
So let's just say you're sitting in a chair.
link |
You're going to look up towards the ceiling
link |
and your eyes will just go there.
link |
You're doing this eyes open and you look down.
link |
Now try doing it really, really slowly.
link |
Some people even get motion sick doing this,
link |
which if you do, then just stop, okay?
link |
So you can do this also to the side,
link |
although it works best if you're moving your head
link |
from side to side or nodding up and down.
link |
So what we're doing here
link |
is we're uncoupling these two mechanisms.
link |
We're pulling them apart, the visual part
link |
and the vestibular part, just to illustrate to you
link |
that normally these mechanisms in your inner ear
link |
tell your eyes where to go,
link |
but as well, your eyes tell your balance system,
link |
your vestibular system, how to function.
link |
So I'd like you to do a different experiment.
link |
I'm not going to do it right now, but basically stand up.
link |
If you get the opportunity,
link |
you can do this safely wherever you are.
link |
You're going to stand up
link |
and you're going to look forward about 10, 12 feet.
link |
Pick a point on a wall or you can, anywhere that you like.
link |
If you're out in public, just do it anyway.
link |
Just tell them you're listening to Huberman Lab Podcast
link |
and someone's telling you to do it.
link |
Anyway, if you don't want to do it, don't do it,
link |
but basically do it.
link |
Stand on one leg and lift up the other leg.
link |
You can bend your knee if you like,
link |
and just look off into the distance about 10, 12 feet.
link |
If you can do that, if you can stand on one leg,
link |
now close your eyes.
link |
Chances are you're going to suddenly feel
link |
what scientists call postural sway.
link |
You're going to start swaying around a lot.
link |
It is very hard to balance with your eyes closed.
link |
You might think, well, and if you think about that,
link |
it's like, why is that?
link |
Why would it be that it's hard to balance
link |
with your eyes closed?
link |
Well, information about the visual world
link |
also feeds back onto this vestibular system.
link |
So the vestibular system informs your vision
link |
and tells you where to move your eyes,
link |
and your eyes and their positioning
link |
tell your balance system, your vestibular system,
link |
how it should function.
link |
So there's a really cool way
link |
that you can learn to optimize balance.
link |
You're not going to try and do this
link |
by learning to balance with your eyes closed.
link |
What you can do is you can raise one leg,
link |
and you can look at a short distance,
link |
maybe off to just the distance that your thumb would be
link |
if you were to reach your arm out in front of you,
link |
although you don't necessarily have to put your thumb
link |
So maybe just about two feet in front of you.
link |
Then while still balancing,
link |
you're going to step your vision out a further distance,
link |
and then a further distance,
link |
and as far as you can possibly see
link |
in the environment that you're in.
link |
And then you're going to march it back to you.
link |
Now, what the literature shows
link |
is that this kind of balance training
link |
where you incorporate the visual system
link |
and extending out and then marching back in,
link |
the point at which you direct your visual focus,
link |
sends robust information about the relationship
link |
between your visual world and your balance system.
link |
And of course, the balance system includes
link |
not just these hula hoops, these semicircular canals,
link |
but they communicate with the cerebellum,
link |
the so-called mini brain actually means mini brain
link |
in the back of your brain,
link |
combines that with visual information
link |
and your map of the body surface.
link |
That pattern of training is very beneficial
link |
for enhancing your ability to balance
link |
because the ability to balance is in part
link |
the activation of particular postural muscles,
link |
but just as much, perhaps even more so,
link |
it's about being able to adjust those postural muscles,
link |
excuse me, it's about the ability
link |
to adjust those postural muscles
link |
as you experience changes in your visual world.
link |
And one of the most robust ways that you can engage changes
link |
in your visual world is through your own movement.
link |
And so most people are not trying to balance in place.
link |
They're not just trying to stand there
link |
like a statue on one leg.
link |
Most of what we think about when we think about balance
link |
is for sake of sport or dynamic balance,
link |
of being able to break ourselves
link |
and when we're lunging in one particular direction
link |
to stop ourselves, that is,
link |
and then to move in another direction
link |
or for skateboarding or surfing or cycling
link |
or any number of different things, gymnastics.
link |
So the visual system is the primary input
link |
by which you develop balance,
link |
but you can't do it just with the visual system.
link |
So what I'm recommending is if you're interested
link |
in cultivating a sense of balance,
link |
understand the relationship between
link |
these semicircular canals.
link |
Understand that they are both driving eye movements
link |
and they are driven by eye movements.
link |
It's a reciprocal relationship.
link |
And then even just two or three minutes a day
link |
or every once in a while, even three times a week,
link |
maybe five minutes, maybe 10 minutes, you pick.
link |
But if you want to enhance balance,
link |
you have to combine changes in your visual environment
link |
with a static posture, standing on one leg
link |
and shifting your visual environment
link |
or static visual view, looking at one thing
link |
and changing your body posture, okay?
link |
So those two things we now know
link |
from the scientific literature combine
link |
in order to give an enhanced sense of balance.
link |
And there's a really nice paper that was published in 2015
link |
called Effects of Balance Training on Balance Performance.
link |
This was in Healthy Adults.
link |
It's a systematic review and a meta-analysis.
link |
A meta-analysis is when you combine a lot of literature
link |
from a lot of different papers
link |
and extract the really robust
link |
and the less robust statistical effects.
link |
So it's a really nice paper as well.
link |
There are some papers out there, for instance,
link |
a comparison of static balance
link |
and the role of vision in the elite athletes.
link |
This is essentially the paper that I've extracted
link |
most of the information that I just gave you from.
link |
And that paper, and there are some others as well,
link |
but basically I distilled them down
link |
into their core components.
link |
The core components are move your vision around
link |
while staying static still,
link |
but in a balanced position like standing on one leg.
link |
Could be something more complicated
link |
if you're somebody who can do more complicated movements.
link |
Unilateral movements seem to be important.
link |
So standing on one leg as opposed to both, right?
link |
Or trying to generate some tilt
link |
is another way to go about it or imbalance,
link |
meaning one limb asymmetrically being activated
link |
compared to the other limb.
link |
And then the other way to encourage or to cultivate
link |
and build up this vestibular system
link |
and your sense of balance
link |
actually involves movement itself, acceleration.
link |
So that's what we're going to talk about now.
link |
So up until now, I've been talking about balance
link |
only in the static sense,
link |
like standing on one leg, for instance,
link |
but that's a very artificial situation.
link |
Even though you can train balance that way,
link |
most people who want to enhance their sense of balance
link |
for sport or dance or some other endeavor
link |
want to engage balance in a dynamic way,
link |
meaning moving through lots of different planes of movement,
link |
maybe even sometimes while squatting down low
link |
or jumping and landing
link |
or making trajectories that are different angles.
link |
For that, we need to consider that the vestibular system
link |
also cares about acceleration.
link |
So it cares about head position,
link |
it cares about eye position
link |
and where the eyes are and where you're looking,
link |
but it also cares about what direction you're moving
link |
And one of the best things that you can do
link |
to enhance your sense of balance
link |
is to start to bring together your visual system,
link |
the semicircular canals of the inner ear,
link |
and what we call linear acceleration.
link |
So if I move forward in space rigidly upright,
link |
it's a vastly different situation
link |
than if I'm leaning to the side.
link |
One of the best ways to cultivate a better sense of balance,
link |
literally, within the sense organs and the neurons
link |
and the biology of the brain
link |
is to get into modes where we are accelerating forward,
link |
typically it's forward,
link |
while also tilted with respect to gravity.
link |
Now, this would be the carve on a skateboard
link |
or on a surfboard or a snowboard.
link |
This would be the taking a corner on a bike
link |
while being able to lean safely, of course,
link |
lean into the turn so that your head is actually tilted
link |
with respect to the earth.
link |
So anytime that we are rigidly upright,
link |
we aren't really exercising the vestibular system and balance.
link |
This is why, you know, you see people in the gym on these,
link |
what are those Bonshi balls, Bonshi balls?
link |
Bonshi ball's the one that the guys roll in the park, right?
link |
Bonshi balls where they're balancing back and forth.
link |
That will work the small stabilizing muscles.
link |
But what I'm talking about is getting into modes
link |
where you actually tilt the body and the head
link |
with respect to earth.
link |
What I mean is with respect to earth's gravitational pull.
link |
Now, the cerebellum is a very interesting structure
link |
because not only is it involved in balance,
link |
but it's also involved in skill learning
link |
and in generating timing of movements.
link |
It's a fascinating structure deserving of an entire episode
link |
or several episodes all on its own.
link |
But some of the outputs of the cerebellum,
link |
meaning the neurons in the cell cerebellum get inputs,
link |
but they also send information out.
link |
The outputs of the cerebellum are strongly linked
link |
to areas of the brain that release neuromodulators
link |
that make us feel really good,
link |
in particular, serotonin and dopamine.
link |
And this is an early emerging subfield within neuroscience,
link |
but a lot of what are called the non-motor outputs
link |
of the cerebellum have a profound influence,
link |
not just on our ability to learn how to balance better,
link |
but also how we feel overall.
link |
So for you exercisers out there,
link |
I do hope people are getting
link |
regular healthy amounts of exercise.
link |
We've talked about what that means in previous episodes.
link |
So at least 150 minutes a week of endurance work,
link |
some strength training, a minimum of five sets per body part
link |
to maintain musculature.
link |
Even if you don't want to grow muscles,
link |
you want to do that in order to maintain
link |
healthy strength and bones, et cetera.
link |
If you're doing that,
link |
but you're only doing things like curls in the gym,
link |
squats in the gym, riding the Peloton,
link |
or even if you're outside running
link |
and you're getting forward acceleration,
link |
but you're never actually getting tilted, right?
link |
You're never actually getting tilted
link |
with respect to Earth's gravitational pull.
link |
You're not really exercising
link |
and getting the most out of your nervous system.
link |
Activation of the cerebellum in this way of being tilted
link |
or the head being tilted and the body being tilted
link |
while in acceleration, typically forward acceleration,
link |
but sometimes side to side,
link |
has a profound and positive effect
link |
on our sense of mood and wellbeing.
link |
And as I talked about in a previous episode,
link |
it can also enhance our ability to learn information
link |
in the period after generating those tilts
link |
and the acceleration.
link |
And that's because the cerebellum has these outputs
link |
to these areas of the brain
link |
that release these neuromodulators
link |
like serotonin and dopamine,
link |
and they make us feel really good.
link |
I think this is one of the reasons why growing up,
link |
I had some friends, some of whom might've been
link |
the world heavyweight champions of laziness
link |
for essentially everything,
link |
except they would wake up at 4.30 in the morning
link |
They would drive, they would get up so early to go surf.
link |
It's not just surfers, and some surfers, by the way,
link |
I should point out are not lazy humans.
link |
They do a lot of other things,
link |
but I knew people that couldn't be motivated to do anything,
link |
but they were highly driven to get into these experiences
link |
of forward acceleration while tilted
link |
with respect to gravity.
link |
Likewise with snowboarding or skiing or cycling,
link |
those modes of exercise seem to have an outsized effect
link |
both on our wellbeing and our ability
link |
to translate the vestibular balance
link |
that we achieve in those endeavors
link |
to our ability to balance while doing other things.
link |
So, and I don't mean psychological balance necessarily,
link |
I mean physical balance.
link |
So for those of you that don't think of yourselves
link |
as very coordinated or with very good balance,
link |
getting into these modes of acceleration,
link |
forward movement or lateral movement while getting tilted,
link |
even if you have to do it slowly, could be beneficial,
link |
I do believe, and the scientific literature points
link |
to the fact that it will be beneficial
link |
for cultivating better sense of physical balance.
link |
It can really build up the circuits
link |
of this vestibular system.
link |
And then of course the feel-good components
link |
of acceleration while tilted
link |
or while getting the head into different orientations
link |
relative to gravity.
link |
Well, that's the explanation for roller coasters.
link |
Some people hate roller coasters,
link |
they make them feel nauseous.
link |
Many people love roller coasters.
link |
And one of the reasons they love roller coasters
link |
is because of the way that when you get the body,
link |
even if you're not generating the movement,
link |
you get the body into forward acceleration
link |
and you're going upside down and tilted to the side
link |
as the tracks go from side to side and tilt, et cetera,
link |
you're getting activation of these deeper brain nuclei
link |
that trigger the release of neuromodulators
link |
that just make us feel really, really good.
link |
In fact, some people get a long arc, a long duration
link |
kind of buzz from having gone through those experiences.
link |
Some people who hate roller coasters
link |
are probably getting nauseous just hearing about that.
link |
So I encourage people to get into modes of acceleration
link |
while tilted every once in a while,
link |
provided you can do it safely.
link |
It's an immensely powerful way to build up your skills
link |
in the realm of balance.
link |
And it's also, for most people, very, very pleasing.
link |
It feels really good because of the chemical relationship
link |
between forward acceleration and head tilt and body tilt.
link |
Now, speaking of feeling nauseous, some people suffer
link |
from vertigo, some people feel dizzy,
link |
some people get lightheaded.
link |
An important question to ask yourself always
link |
if you're feeling quote unquote dizzy or lightheaded is,
link |
are you dizzy or are you lightheaded?
link |
Now, we're not going to diagnose anything here
link |
because there's just no way we can do that.
link |
This is essentially me shouting into a tunnel
link |
so we don't know what's going on
link |
with each and every one of you.
link |
But if ever you feel that your world is spinning,
link |
but that you can focus on your thumb, for instance,
link |
but the rest of the world is spinning
link |
and your thumb is stationary, that's called being dizzy.
link |
Now, if you feel like you're falling
link |
or that you feel like you need to get down onto the ground
link |
because you feel lightheaded, that's being lightheaded.
link |
And oftentimes with language, we don't distinguish
link |
between being dizzy and being lightheaded.
link |
Now, there are a lot of ways that dizziness
link |
and lightheadedness can occur.
link |
And I don't even want to begin to guess
link |
at the number of different things and ways
link |
that it could happen for those of you that suffer from it
link |
because it could be any number of them.
link |
But oftentimes if people are lightheaded,
link |
yes, it could be low blood sugar.
link |
It could also be that you're dehydrated.
link |
It could also be that you are low in electrolytes.
link |
We talked about this in a previous episode,
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but we will talk about it more in a future episode.
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Many people have too little sodium in their system, salt,
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and that's why they feel lightheaded.
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I have family members who for years
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thought they had disrupted blood sugar.
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They would get shaky, jittery, lightheaded,
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feel like they were nauseous, et cetera.
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And simply the addition of a little sea salt
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to their water remedied the problem entirely.
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I don't think it's going to remedy every issue
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of lightheadedness out there by any stretch,
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but just the addition of salt in this particular case
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helped the person and they are not alone.
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Many people would think that they have low blood sugar
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actually are lightheaded because of low electrolytes
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and because of the way that salt carries water
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into the system and creates changes in blood volume, et cetera
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low sodium can often be a source of lightheadedness
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as can low blood sugar and of course other things as well.
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Now for dizziness or seasickness,
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we were all taught that you need to pick a point
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on the horizon and focus on it.
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But actually that's not correct.
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It is true that if you are down in the cabin of a boat
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or you're on the lower deck
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and all you can see are things up close to you
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that getting sloshed around like so
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or the boat going up and down like so,
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I think I'm getting a little seasick
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even as I do this and I describe it.
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Focusing on things close to you can be problematic.
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And in that case, the advice to go up on deck
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and get fresh air and to look off into the horizon,
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that part is correct.
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But focusing your eyes on a particular location
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on the horizon is effectively like trying
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to move very slowly as I had you do before
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where you're trying to move your head very slowly
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while fixating on one location.
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Your eyes and your balance system
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were designed to move together.
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So really what you want to do is allow your visual system
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to track with your vestibular system.
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This is why sitting in the back of an Uber or a taxi
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and being on your phone
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can make you suddenly feel very nauseous.
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Sometimes the cabs, particularly in New York City,
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they have a lot of occluders.
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They have a lot of stuff blocking your field of view.
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There's usually a little portal out
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that where you can see out to the front windshield,
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but there's all this stuff now.
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Television's in the back seat
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and you're watching that television and the cab is moving.
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You're in linear acceleration
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and sometimes you're taking corners, you're braking.
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So then your vestibular system has to adjust to that.
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If you're looking at your phone or a book,
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or even if you're talking to somebody,
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actually, I'm starting to feel a little nauseous.
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I promise I'm not going to finish this episode
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by vomiting at the end, at least not here.
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But what can happen is that you're uncoupling
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the visual information from your motion,
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from your vestibular information.
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You want those to be coupled.
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This is why a lot of people have to drive.
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They can't be in the passenger seat
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because when you drive,
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you also get what's called proprioceptive feedback.
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Your body is sending signals also to the vestibular system
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about where you are in space.
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When you're the passenger,
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you're just getting jolted around as the person is driving.
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And if you're looking at your phone, it's even worse.
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And if you're looking at the occluder
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between you and the two front seats, that's even worse.
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So this is why staring out the front windshield is great,
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but you don't want to fixate, okay?
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So hopefully I spared a few people
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and hopefully a few cab drivers
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of having people get sick in their cars or Ubers.
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Let your visual system
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and your vestibular system work together.
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If appropriate, get into linear acceleration
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and you'll improve your sense of balance.
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Once again, we've covered a tremendous amount
link |
Now you know how you hear,
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how you make sense of the sounds in your environment,
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how those come into your ears
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and how your brain processes them.
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In addition, we talked about things
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like low-level white noise and even binaural beats,
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which can be used to enhance certain brain states,
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certain rhythms within the brain and even dopamine release
link |
in ways that allow you to learn better.
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And we talked about the balance system
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and this incredible relationship
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between your vestibular apparatus,
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meaning the portions of your inner ear
link |
that are responsible for balance
link |
and your visual system and gravity.
link |
And you can use those to enhance your learning as well,
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as well as just to enhance your sense of balance.
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If you're learning from this podcast,
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please subscribe on YouTube.
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That really helps us.
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In addition, please leave us any comments or feedback
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or suggestions for future episode content on YouTube
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in the comment section.
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If you haven't already subscribed on Apple and Spotify,
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please do that as well.
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And on Apple, you have the opportunity
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to leave us up to a five-star review.
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At Apple, you can also leave us comments and feedback.
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During this episode, I mentioned some supplements.
link |
We partnered with Thorne
link |
because Thorne has the very highest levels of stringency
link |
with respect to the quality of their ingredients
link |
and accuracy about the amounts of those ingredients
link |
contained within their products.
link |
If you'd like to see the products that I take from Thorne,
link |
you can go to thorne.com slash the letter U slash Huberman.
link |
So that's thorne.com slash U slash Huberman
link |
to see all the supplements that I take.
link |
And if you do that,
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you can get 20% off any of those supplements
link |
or 20% off any of the supplements that Thorne makes.
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For those of you that might want to support us
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in other ways, we have a Patreon account.
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It's patreon.com slash Andrew Huberman.
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And there you can support our podcast
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at any level that you like.
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In addition, if you'd like to support the podcast,
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please check out our sponsors mentioned
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at the beginning of the episode.
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That is absolutely the best way to support us.
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Last but not least,
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I'd like to thank you for your time and attention
link |
and desire and willingness to learn
link |
about vision and balance.
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And of course, thank you for your interest in science.
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And as always, thanks for watching.