Essentials: How Hearing & Balance Enhance Focus & Learning

ANDREW HUBERMAN: Welcome to Huberman Lab Essentials, where we revisit past episodes for the most potent and actionable science-based tools for mental health, physical health, and performance. I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. Today, we're going to talk all about hearing and balance and how you can use your ability to hear specific things and your balance system in order to learn anything faster.

The auditory system, meaning the hearing system, and your balance system, which is called the vestibular system, interact with all the other systems of the brain and body and, used properly, can allow you to learn information more quickly, remember that information longer and with more ease, and you can also improve the way you can hear. You can improve your balance. We're going to talk about tools for all of that.

Can you hear me? Can you hear me? OK, well, if you can hear me, that's amazing because what it means is that my voice is causing little tiny changes in the airwaves wherever you happen to be and that your ears and whatever's contained in those ears and in your brain can take those sound waves and make sense of them. And that is an absolutely fantastic and staggering feat of biology. And yet we understand a lot about how that process works.

So what we call ears have a technical name. That technical name is oracles, but more often they're called pinna, the pinnas, P-I-N-N-A, pinna. And the pinnas of your ears, this outer part that is made of cartilage and stuff, is arranged such that it can capture sound in the best way for your head size.

So the shape of these ears that we have is such that it amplifies high-frequency sounds. High-frequency sounds, as the name suggests, is the squeakier stuff. So we have low-frequency sounds and high-frequency sounds and everything in between.

And those sound waves, for those of you that don't maybe fully conceptualize sound waves, are literally just fluctuations or shifts in the way that air is moving toward your ear and through space. In the same way that water can have waves, the air can have waves. So it's reverberation of air.

Those come in through your ears, and you have what's called your eardrum. And on the inside of your eardrum, there's a little bony thing that's shaped like a little hammer. So attached to that eardrum, which can move back and forth like a drum-- it's like a little membrane-- you've got this hammer attached to it. And that hammer has three parts.

For those of you that want to know, those three parts are called malleus, incus, and stapes. But basically, you can just think about it as a hammer. So you've got this eardrum and then a hammer, and then that hammer has to hammer on something. And what it does is it hammers on a little coiled piece of tissue that we call the cochlea. So this snail-shaped structure in your inner ear is where sound gets converted into electrical signals that the brain can understand.

Now, the cochlea at one end is more rigid than the other. So one part can move really easily, and the other part doesn't move very easily. And that turns out to be very important for decoding or separating sounds that are of low frequency and sounds that are of high frequency, like a shriek or a shrill. And that's because within that little coiled thing we call the cochlea, you have all these tiny little what are called hair cells.

Now, they look like hairs, but they're not at all related to the hairs on your head or elsewhere on your body. They're just shaped like hairs, so we call them hair cells. Those hair cells, if they move, send signals into the brain that a particular sound is in our environment.

Now, this should stagger your mind. If it doesn't already, it should because what this means is that everything that's happening around us, whether or not it's music or voices, all of that is being broken down into its component parts, and then your brain is making sense of what it means. Your cochlea essentially acts as a prism. It takes all the sound in your environment, and it splits up those sounds into different frequencies.

And then the brain takes that information and puts it back together and makes sense of it. So those hair cells in each of your two cochlea-- because you have two ears, you also have two cochlea-- send little wires, what we call axons, that convey their patterns of activity into the brain. And there are a number of different stations within the brain that information arrives at before it gets up to the parts of your brain where you are consciously aware.

And there is a good reason for that, which is that more important than knowing what you're hearing, you need to know where it's coming from. And our visual system can help with that. But our auditory and our visual system collaborate to help us find and locate the position of things in space.

That should come as no surprise. If you hear somebody talking off to your right, you tend to turn to your right, not to your left. If you see somebody's mouth moving in front of you, you tend to assume that the sound is going to come from right in front of you.

Disruptions in this auditory, hearing, and visual matching are actually the basis of what's called the ventriloquism effect. The ventriloquism effect can basically be described in simple terms as when you essentially think that a sound is coming from a location that it's not actually coming from. The way you know where things are coming from, what direction a car or a bus or a person is coming from, is because the sound lands in one ear before the other. And you have stations in your brain, meaning you have neurons in your brain, that calculate the difference in time of arrival for those sound waves in your right versus your left ear.

And if they arrive at the same time, you assume that thing is making noise right in front of you. If it's off to your right, you assume it's over on your right. And if the sound arrives first to your left ear, you assume quite correctly that the thing is coming toward your left ear.

But what about up and down? If you think about it, a sound coming from above is going to land on your right ear and your left ear at the same time. A sound from below is going to land on your right ear and your left ear at the same time. So the way that we know where things are in terms of what's called elevation, where they are in the up and down plane, is by the frequencies. The shape of your ears actually modifies the sound depending on whether or it's coming straight at you from the floor or from high above.

Now, this all happens very, very fast, and it's subconscious. But now you know why if people really want to hear something, they make a cup around their ear. They essentially make their ear into more of a fennec fox type ear.

If you've ever seen those cute little fennec fox things, they have these big spiky ears. They look like a French bulldog, although they're the fox version of the French bulldog. These big, tall ears, and they have excellent sound localization.

And so when people lean in with their ear like this-- with their hand like this-- if you're listening to this, I'm just cupping my hand at my ear-- I'm giving myself a bigger pinna. Again, if I do it on the left side, I can do this side. And if I really want to hear something, I do it on both sides.

So this isn't just gesturing. This actually serves a mechanical role. And actually, if you want to hear where things are coming from with a much greater degree of accuracy, this can actually help because you're capturing sound waves and funneling them better.

So now I want to shift to talking about ways to leverage your hearing system, your auditory system, so that you can learn anything, not just auditory information, but anything faster. I get a lot of questions about so-called binaural beats. Binaural beats, as their name suggests, involve playing one frequency of sound to one ear and a different frequency of sound to the other ear.

And the idea is that the brain will take those two frequencies of sound. And because the pathways that bring information from the ears into the brain eventually cross over-- they actually share that information with both sides of the brain-- that the brain will average that information and come up with a sort of intermediate frequency. And the rationale is that those intermediate frequencies place the brain into a state that is better for learning.

And when I say better for learning, I want to be precise about what I mean. That could mean more focus for encoding or bringing the information in. As you may have heard me say before, we have to be alert and focused in order to learn.

So can binaural beats make us more focused? Can binaural beats allow us to relax more if we're anxious? So what does the scientific data say about binaural beats?

The science on binaural beats is actually quite extensive and very precise. So sound waves are measured typically in hertz or kilohertz. I know many of you aren't familiar with thinking about things in hertz or kilohertz, but again, just remember those waves on a pond, those ripples on a pond. If they're close together, then they are of high frequency. And if they're far apart, then they are of low frequency. So if it's many more kilohertz, then it's much higher frequency than if it's fewer hertz or kilohertz.

And so you may have heard of these things as delta waves or theta waves or alpha waves or beta waves, et cetera. Delta waves would be big, slow waves, so low frequency. And indeed there is quality evidence from peer-reviewed studies that tell us that delta waves like 1 to 4 hertz, so very low frequency sounds, can help in the transition to sleep and for staying asleep, and that theta rhythms, which are more like 4 to 8 hertz, can bring the brain into a state of subtle sleep or meditation, so deeply relaxed but not fully asleep.

And you'll find evidence that alpha waves, 8 to 13 hertz, can increase alertness to a moderate level-- that's a great state for the brain to be in for recall of existing information-- and that beta waves, 15 to 20 hertz, are great for bringing the brain into focus states for sustained thought or for incorporating new information. And especially gamma waves, the highest frequency, the most frequent ripples of sound, so to speak, 32 to 100 hertz, for learning and problem-solving.

Here, we're talking about the use of binaural beats in order to increase our level of alertness or our level of calmness. Now, that's important to underscore because it's not that there's something fundamentally important about the binaural beats. They are yet another way of bringing the brain into states of deep relaxation through low-frequency sound or highly alert states for focused learning with more high-frequency sound. They're effective, but it's not that they're uniquely special for learning. It's just that they can help some people bring their brain into the state that allows them to learn better.

There's very good evidence for anxiety reduction from the use of binaural beats. And what's interesting is the anxiety reduction seems to be most effective when the binaural beats are bringing the brain into delta-- so those slow, big waves like sleep-- theta, and alpha states. There's good evidence that binaural beats can be used to treat pain, chronic pain.

But the real boost from binaural beats appears to be for anxiety reduction and pain reduction. Many people like binaural beats and say that they benefit from them, especially while studying or learning. I think part of the reason for that relates to the ability to channel our focus when we have some background noise.

And this is something I also get asked about a lot. Is it better to listen to music and have background noise when studying, or is it better to have complete silence? Well, there's actually a quite good literature on this as well but not so much as it relates to binaural beats but rather whether or not people are listening to music, so-called white noise, brown noise. Believe it or not, there's white noise, and there's brown noise. There's even pink noise.

I want to be very clear that white noise has been shown to really enhance brain states for learning in certain individuals, in particular in adults. But white noise actually can have a detrimental effect on auditory learning and maybe even the development of the auditory system in very young children, in particular in infants. So first, I'd like to talk about the beneficial effects of white noise on learning.

There are some really excellent studies on this. The first one that I'd like to just highlight is one that's entitled "Low-intensity white noise improves performance in auditory working memory task: An fMRI study." This is a study that explored whether or not learning could be enhanced by playing white noise in the background.

But the strength of the study is that they looked at some of the underlying neural circuitry and the activation of the neural circuitry in these people as they did the learning task. And what it essentially illustrates is that white noise, provided that white noise is of low enough intensity, meaning not super loud, it actually could enhance learning to a significant degree. And this has been shown now for a huge number of different types of learning.

I was very relieved to find, or I should say excited to find, this study published in the Journal of Cognitive Neuroscience. This is a 2014 paper. "White noise improves learning by modulating activity in dopaminergic midbrain regions and the right superior temporal sulcus."

I don't expect you to know what the dopamine midbrain region is, but if you're like me, you probably took highlighted notice of the word "dopaminergic." Dopamine is a neuromodulator, meaning it's a chemical that's released in our brain and body, but mostly in our brain, that modulates, meaning controls, the likelihood that certain brain areas will be active and other brain areas won't be active. And dopamine is associated with motivation. Dopamine is associated with craving. But what's so interesting to me is that it appears that white noise itself can raise what we call the basal, the baseline levels of dopamine that are being released from this area, the substantia nigra.

So now we're starting to get a more full picture of how particular sounds in our environment can increase learning, and that's in part, I believe, through the release of dopamine from substantia nigra. So I'm not trying to shift you away from binaural beats if that's your thing, but it does appear that turning on white noise at a low level, but not too loud, can allow you to learn better because of the ways that it's modulating your brain chemistry.

So what about white noise and hearing loss in development? I know a lot of people with children have these noise machines, sound waves, and things like that that help the kids sleep. And look, I think kids getting good sleep and parents getting good sleep is vital to physical and mental health and family health, so I certainly sympathize with those needs.

However, there are data that indicate that white noise during development can be detrimental to the auditory system. I don't want to frighten any parents. If you played white noise to your kids, this doesn't mean that their auditory system or their speech patterns are going to be disrupted or that their interpretation of speech is going to be disrupted forever.

But there are data published in the Journal Science some years ago showing that when they exposed very young animals to this white noise, it actually disrupted the maps of the auditory world within the brain. So auditory information goes up into our cortex, into these-- essentially the outside portion of our brain that's responsible for all of our higher-level cognition, our planning, our decision-making, et cetera, creativity. And up there, we have what are called tonotopic maps. What's a tonotopic map?

Well, remember the cochlea, how it's coiled, and at one end, it responds to high frequencies, and the other end, it responds to low frequencies, like a piano? In the auditory system, we have what are called tonotopic maps, where frequency-- high frequency to low frequency and everything in between-- is organized in a very systematic way. Now, our experience of life from the time we're a baby until the time that we die is not systematic. We don't hear low frequencies at one part of the room or at one part of the day, and high frequencies in another part of the room and another part of the day. They're all intermixed.

But if you remember, the cochlea separates them out. Just like a prism of light separates out the different wavelengths of light, the cochlea separates out the different frequencies. And the developing brain takes those separated-out frequencies and learns this relationship between itself, meaning the child, and the outside world. White noise essentially contains no tonotopic information. The frequencies are all intermixed. It's just noise.

So one of the reasons why hearing a lot of white noise during development for long periods of time can be detrimental to the development of the auditory system is that these tonotopic maps don't form normally. At least they don't in experimental animals. Now, the reason I'm raising this is that many people I know, in particular friends who have small children, they say, I want to use a white noise machine while I sleep. But is it OK for my baby to use a white noise machine?

And I consulted with various people-- scientists about this, and they said, well, the baby is also hearing the parent's voices and is hearing music and is hearing the dog bark. So it's not the only thing they're hearing.

However, every single person that I consulted with said, but there's neuroplasticity during sleep. That's when the kid is sleeping. And I don't know that you'd want to expose a child to white noise the entire night because it might degrade that tonotopic map. It might not destroy it, it might not eliminate it, but it could make it a little less clear, like taking the keys on the piano and taping a few of them together.

Once your auditory system has formed, once it's established these tonotopic maps, then the presence of background white noise should not be a problem at all. In fact, it shouldn't be a problem at all because you're also not attending to it. The idea is that it's playing at a low enough volume that you forget it in the background and that it's supporting learning by bringing your brain into a heightened state of alertness and especially this heightened state of dopamine-- dopaminergic activation of the brain, which will make it easier to learn faster and easier to learn the information.

So now I want to talk about auditory learning and actually how you can get better at learning information that you hear, not just information that you see on a page, or motor skill learning. So there's a phenomenon called the cocktail party effect. Now, even if you've never been to a cocktail party, you've experienced and participated in what's called the cocktail party effect.

The cocktail party effect is where you are in an environment that's rich with sound, many sound waves coming from many different sources, many different things, so in a city, in a classroom, in a car that contains people having various conversations. You somehow need to be able to attend to specific components of those sound waves, meaning you need to hear certain people and not others. You and your brain are exquisitely good at creating a cone of auditory attention, a narrow band of attention with which you can extract the information you care about and wipe away or erase all the rest.

Now, this takes work. It takes attention. One of the reasons why you might come home from a loud gathering-- maybe a stadium, a sports event, or a cocktail party for that matter-- and feel just exhausted is because if you were listening to conversations there or trying to listen to those conversations while watching the game, it takes attentional effort, and the brain uses up a lot of energy just at rest, but it uses up even more energy when you are paying strong attention to something, literally caloric energy burning up things like glucose, et cetera. Even if you're ketogenic, it's burning up energy.

So the cocktail party effect has been studied extensively in the field of neuroscience, and we now know at a mechanistic level how one accomplishes this feat of attending to certain sounds despite the fact that we are being bombarded with all sorts of other sounds. So there are a couple of ways that we do this. First of all, much as with our visual system, we can expand or contract our visual field of view.

We can do that. We can expand and contract our visual field of view. Well, we can expand and contract our auditory field of view, so to speak, or our auditory window. We can really hear one person or a small number of people amidst a huge background of chatter because we pay attention to the onset of words but also to the offset of words.

So one of the more common phenomena that I think we all experience is you go to a party, and/or you meet somebody new, and you say hi. I would say, hi, I'm Andrew, and they'd say, hi, I'm Jeff, for instance. Great to meet you. And then a minute later, I can't remember the guy's name.

Now, is it because I don't care what his name is? No. Somehow the presence of other auditory information interfered. It's not that my mind was necessarily someplace else. It's that the signal to noise, as we say, wasn't high enough. Somehow the way he said it or the way it landed on my ears, which is really all that matters when it comes down to learning, is such that it just didn't achieve high enough signal to noise.

So the next time you ask somebody's name, remember, listen to the onset of what they say and the offset. So it would be paying attention to the "juh" in "Jeff," and it would be paying attention to that "fff" in F-- in "Jeff," excuse me. All right? And chances are you'll be able to remember that name.

Now, I do acknowledge that trying to learn every word in a sentence by paying attention to its onset and offset could actually be disruptive to the learning process. So this would be more for specific attention. Using the attentional system, we can actually learn much faster, and we can actually activate neuroplasticity in the adult brain, something that's very challenging to do, and that the auditory system is one of the main ways in which we can access neuroplasticity more broadly.

I'd like to now talk about balance and our sense of balance, which is controlled by, believe it or not, our ears and things in our ears, as well as by our brain and elements of our spinal cord. The reason why we're talking about balance and how to get better at balancing in the episode about hearing is that all the goodies that are going to allow you to do that are in your ears. They're also in your brain, but they're mostly in your ears.

So as you recall from the beginning of this episode, you have two cochleas that are-- one on each side of your head. And that's a little spiral snail-shaped thing that converts sound waves into electrical signals that the rest of your brain can understand. Right next to those, you have what are called semicircular canals.

The semicircular canals can be best visualized as thinking about three hula hoops with marbles in them. So imagine that you have a hula hoop, and it's not filled with marbles all the way around. It's just got some marbles down there at the base.

So if you were to move that hula hoop around, one of those hula hoops is positioned vertically with respect to gravity. But basically, it's upright. Another one of those hula hoops is basically at a 90-degree angle, basically parallel to the floor if you're standing up right now if you're seated.

And the other one is tilted about 45 degrees in between those. Now, why is this system there? Well, those marbles within each one of those hula hoops can move around, but they'll only move around if your head moves in a particular way.

And there are three planes or three ways that your head can move. Your head can move up and down like I'm nodding right now. So that's called pitch. Or I can shake my head, no, side to side. That's called yaw. And then there's roll-- tilting the head from side to side the way that a cute puppy might look at you from side to side.

Pitch, yaw, and roll are the movements of the head in each of the three major planes of motion, as we say, and each one of those causes those marbles to move in one or two of the various hula hoops. They aren't actually marbles, by the way. These are little stones, basically, little calcium-like deposits. And when they roll back and forth, they deflect little hairs, little hair cells that aren't like the hair cells that we use for measuring sound waves, but they're basically rolling past these little hair cells and causing them to deflect.

And when they deflect downward, the neurons, because hair cells are neurons, send information up to the brain. So if I move my head like this, there's a physical movement of these little stones in this hula hoop, as I'm referring to it, but they deflect these hairs, send those hairs, which are neurons-- those hair cells send information off to the brain. Any animal that has a jaw has this so-called balance system, which we call the vestibular system.

One of the more important things to know about the vestibular, the balance system, is that it works together with the visual system. Let's say I hear something off to my left, and I swing my head over to the left to see what it is. There are two sources of information about where my head is relative to my body, and I need to know that.

First of all, when I quickly move my head to the side, those little stones, as I'm referring to them, they quickly activate those hair cells in that one semicircular canal and send a signal off to my brain that my head just moved to the side. But also, visual information slid past my field of view. I didn't have to think about it but just slid past my field of view. And when those two signals combine, my eyes then lock to a particular location.

Now, if this is at all complicated, you can actually uncouple these things. It's very easy to do. If you get the opportunity, you can do this safely wherever you are. You're going to stand up, and you're going to look forward about 10, 12 feet. You can pick a point on a wall.

Stand on one leg and lift up the other leg-- you can bend your knee if you like-- and just look off into the distance about 10, 12 feet. If you can do that, if you can stand on one leg, now close your eyes. Chances are you're going to suddenly feel what scientists call postural sway. It is very hard to balance with your eyes closed.

You might think, well-- and if you think about that, it's like, why is that? That's crazy. Why would it be that it's hard to balance with your eyes closed? Well, information about the visual world also feeds back onto this vestibular system. So the vestibular system informs your vision and tells you where to move your eyes, and your eyes and their positioning tell your balance system, your vestibular system, how it should function.

So up until now, I've been talking about balance only in the static sense, like standing on one leg, for instance, but that's a very artificial situation. Even though you can train balance that way, most people who want to enhance their sense of balance for sport or dance or some other endeavor want to engage balance in a dynamic way, meaning moving through lots of different planes of movement.

For that, we need to consider that the vestibular system also cares about acceleration. So it cares about head position, it cares about eye position and where the eyes are and where you're looking, but it also cares about what direction you're moving and how fast. And one of the best things that you can do to enhance your sense of balance is to start to bring together your visual system, the semicircular canals of the inner ear, and what we call linear acceleration.

So if I move forward in space rigidly upright, it's a vastly different situation than if I'm leaning to the side. One of the best ways to cultivate a better sense of balance, literally, within the sense organs and the neurons and the biology of the brain is to get into modes where we are accelerating forward-- typically, it's forward-- while also tilted with respect to gravity. Now, this would be the carve on a skateboard or on a surfboard or a snowboard. This would be the taking a corner on a bike while being able to lean-- safely, of course-- lean into the turn so that your head is actually tilted with respect to the Earth.

The head being tilted and the body being tilted while in acceleration, typically forward acceleration but sometimes side to side, has a profound and positive effect on our sense of mood and well-being. And as I talked about in a previous episode, it can also enhance our ability to learn information in the period after generating those tilts and the acceleration. And that's because the cerebellum has these outputs to these areas of the brain that release these neuromodulators like serotonin and dopamine, and they make us feel really good.

Those modes of exercise seem to have an outsized effect, both on our well-being and our ability to translate the vestibular balance that we achieve in those endeavors to our ability to balance while doing other things. So I encourage people to get into modes of acceleration while tilted every once in a while, provided you can do it safely. It's an immensely powerful way to build up your skills in the realm of balance, and it's also, for most people, very, very pleasing. It feels really good because of the chemical relationship between forward acceleration and head tilt and body tilt.

Once again, we've covered a tremendous amount of information. Now you know how you hear, how you make sense of the sounds in your environment, how those come into your ears, and how your brain processes them. In addition, we talked about things like low-level white noise and even binaural beats, which can be used to enhance certain brain states, certain rhythms within the brain, and even dopamine release in ways that allow you to learn better.

And we talked about the balance system and this incredible relationship between your vestibular apparatus, meaning the portions of your inner ear that are responsible for balance, and your visual system and gravity. And you can use those to enhance your learning as well, as well as just to enhance your sense of balance. Last but not least, I'd like to thank you for your time and attention and desire and willingness to learn about vision and balance. And, of course, thank you for your interest in science.

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