Nina Kraus on Hearing, Noise, and Of Sound Mind
Nov 29 2021

Of-Sound-Mind.jpg We undervalue our sense of hearing and we under-appreciate the impact sweet sounds and disturbing noises have on our well-being. Neuroscientist Nina Kraus of Northwestern University talks about her book, Of Sound Mind. Kraus argues that our listening affects our minds and brains in ways we ignore at our peril.

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Explore audio transcript, further reading that will help you delve deeper into this week’s episode, and vigorous conversations in the form of our comments section below.


krishnan chittur
Nov 29 2021 at 9:18am

Fascinating – enjoyed “hearing” about it.

The computer is crudely like the brain – I imagine the “brain” to be like that “compiler” that takes sound and converts it to some “binary” form that is interpretable by the neurons – e.g. you can ask someone to say “raise your hand” in different languages and people will raise their hand (i.e. the internal, machine language is the same) – but sure, the brain does more that we have yet to understand.

Fascinating to hear about the importance of music for all – not just musicians or those wanting to be one – I know, I derive enormous pleasure from listening and am often transported back in time to when I used to listen in real time in actual classical music festivals – and I imagine it helps me when I transfer my attention to other things that may be more analytical …

thanks …

Joseph Coco
Nov 29 2021 at 1:52pm

1:01:08 It sounds like Nina is discussing heuristics. Most algorithms implemented in computers utilize heuristics. However, aside from advanced machine learning techniques, which often emulate how our brains work, those heuristics have to be hard coded and are not a natural result of a computer operating.

As neural networks become more useful, I’m sure hardware will be more specialized to implement it. GPUs are kind of more like our brains since they can handle matrices data more efficiently. But I believe a subset of computers will become more brain-like, assuming AI continues to be useful.

It’s funny that we think of the Von Neumann machine as being a generalized processor and something more akin to a brain as specialized. I guess it is specialized, just better at abstracting, which current hardware is not good at.

Sorry to fixate on just this. I did enjoy the episode. Russ you should consider reading Shouting Won’t Help by Katherine Bouton.

Shalom Freedman
Nov 30 2021 at 3:09am

The most interesting and disturbing part of this interview centered on the connection between hearing loss and brain transformation, or perhaps even suggested decline. As an elderly person I more and more have to ask again others to repeat what I have said, and too more often feel outside of group conversations. So now hearing aid is more tempting. I would however have liked to hear a bit more about the problems involved in wearing a hearing aid, as I have known not a few people who annoyed by them tossed them into the wastebasket.

Steve Waas
Nov 30 2021 at 3:19pm

Ear surgeries as a kid left me with a partial hearing loss in one ear. Not until this was compounded by age-related hearing loss in my upper 50s did I consider the hearing aid route. At roughly the same time I was also trying to learn a second language, and definitely experienced the “exhaustion” that quickly takes hold when trying to speak and listen to the language for anything more than a few minutes. Like Russ, I too saw the similarities between the language challenge and the listening-with-a-hearing-loss challenge. But I think the major difference is that with the latter, you can never rest from it — it is always present whenever you are trying to communicate with people. Nobody can keep that up for hours on end. Instead, the brain will basically just check out and rely on non-verbal clues as best it can.

The most difficult part of the adjustment is psychological. We just don’t want to be the old person with the hearing aid. But if you are guessing at what people are saying more and more because you’re tired of asking them to repeat, I suggest giving it a shot. It will probably improve your life a lot, and the hit to your ego will dissipate quickly.

Dave Bern
Dec 2 2021 at 12:45am

I was confused by the discussion of ‘b’ vs. ‘p’ and timing.  The concept is well defined in linguistics: ‘b’ is what is called a voiced consonant and ‘p’ is unvoiced.  Yes, the mouth is doing the exact same thing for both, but voiced consonants are produced using the vocal cords while unvoiced are produced by pure aspiration.  This has nothing to do with timing.  There are more pairs: d/t, g/k, z/s, v/f, th:[θ]/[ð] (e.g. this/thing).

Shalom Freedman
Dec 2 2021 at 6:44am

Having commented  once I wonder if I am out of order for commenting again. But listening to this very interesting interview a whole world of thoughts from other areas came to mind. First on the sight versus hearing business. While sight is primary and most important for most people I do not think most of us undervalue hearing. In fact there are cultures and religions which put hearing first. The God of Israel cannot be seen but must be heard. The Jewish people historically have been considered a people who in exile and without a space of their own developed their hearing skills, their poetry and their music more than their skills in the plastic arts.

Nina Kraus
Dec 5 2021 at 6:00pm

Thank you for this comment, Shalom. Indeed, sound has deep historical, religious and biological roots. Among my motivations for writing the book is that many people (you are an exception) have forgotten these important beginnings. I dearly hope you will let me know if I have honored our historical, religious and biological origins while making the case these origins are increasingly overlooked. I just finished reading a book by the philosopher and religious historian Walter Ong called The Presence of the Word: Some Prolegomena for Cultural and Religious History. He talks at length about how the human experience has changed as words have gradually ceased to be sounds and become symbols on pages. If you haven’t read it, you may be interested in what he has to say.

Dave Bern
Dec 4 2021 at 12:25pm

Having finally finished listening to the podcast, I must say that I’m somewhat disappointed.  It was surely entertaining (as a visit to a popsci museum is), but I’m afraid not really the learning experience I’ve come to expect from EconTalk podcasts.  The most value for me is when Russ checks guests’ claims and pushes back to get more details/accuracy.  Since this the topic wasn’t within Russ’s area of expertise, the were no checks, pushbacks, and digging for truth.  There are a few areas in the interview where my knowledge was more than total 0 and I thought Dr. Draus didn’t have the facts right (e.g. voiced vs. unvoiced consonants I mentioned in my previous post).  This makes me wonder what other claims were not correct.

Nina Kraus
Dec 5 2021 at 2:07pm

Dear Dave,

You are entirely correct to point out voice-onset-time is a well known linguistic phenomenon. I discuss it at some length in my book. During the interview, I was referring to the acoustic difference between voiced and unvoiced consonants know as  VOT (voice onset TIME).  In the book I describe how the brain must process this millesecond-long timing difference to distinguish ‘b’ from ‘p’, and ‘d’ from ‘t’. I supplement the text with illustrations.  I hope you will read the book Dave, and get back to me if there is something that does not strike you as correct.

In writing and talking about the book, I have tried to use informal language while at the same time, staying true to the biological and linguistic literature.  You may want to know that 20% of the book consists of citations to published literature.

I do believe your knowledge will enable you to enjoy the book on a deeper layer, which would please me, and more importantly, you.

Bernadette Frenz
Dec 22 2021 at 7:59pm

Dear Ms Kraus, I read the review of your recent book in today’s WSJ, & felt compelled to write. As a woman now in my 60’s, who values music, relationships, & sound in general, incl & perhaps particularly the ways it informs our sense of being in & navigating the world. I have had gradually increasing sensorineural hearing loss since my 20’s, (origin unknown) & eventually succumbed to using a succession of  hearing aids over years. They help but are by no means a panacea, particularly in environments with significant ambient sound load, all of which becomes amplified, & produces a kind of chaos in the brain, as well as the aforementioned fatigue, in the struggle to sort or filter out the undesired sounds. I look forward to reading your book, & am grateful that there are people who are as interested as you are in the world of sound & how we hear, to do the kind of research & work you’re doing. All the ENT’s I’ve seen over the years have been sympathetic, but beyond that, offer little hope beyond the hearing aid. Perhaps in addition to education, your book can also offer a different kind of hope. 

Comments are closed.


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TimePodcast Episode Highlights

Intro. [Recording date: October 27, 2021.]

Russ Roberts: Today is October 27th, 2021, and my guest is author and neuroscientist Nina Kraus of Northwestern University. Her book, and the subject of today's conversation is Of Sound Mind: How Our Brain Constructs a Meaningful Sonic World. Nina, welcome to EconTalk.

Nina Kraus: Well, thank you, Russ. I think you can hear from the sound of my voice how happy I am to be talking to you.


Russ Roberts: This is an utterly fascinating book on a huge part of our daily life that we rarely think about, and often don't fully perceive, which is the role of sound in our lives--music, language, everything else that makes noise--how we hear those sounds, how the brain is shaped by them, and in turn how the brain shapes how we hear.

I want to start with the importance of sound because, as you point out in the book, a lot of people would list it a little bit down the list of their favorite senses. They'd say, 'Eh, seeing, that's crucial. I'd hate to be blind. But, deaf--I could live with it if I had--it's not as important as seeing.' And, I think we hardly ever think about it until we lose our sense of hearing, in which case we do think about it, or if we're deaf. But, I think that one of the themes of your book is that we greatly undervalue the importance of sound and we only think of it as, 'Oh, that's hearing stuff. I get that. I know what I hear. I like to hear things.'

But, it's so much more profound than that, and I think one of the great insights of the book for a non-auditory scientist as you are is to appreciate it. So, why do we undervalue the importance of sound?

Nina Kraus: Yeah. Well, I think one of the reasons is because sound is invisible. And, like many of the powerful forces in our lives, like gravity, you can't see it. We live in an increasingly visually biased world. So, I mean, people just don't recognize and appreciate what an important part sound has in our lives, in our world, and in what makes us, us. And, the book is my love letter to sound.

If you look at the homepage of our website, Brainvolts, you'll see that we study music and bilingualism, aging, language, reading, concussion, hearing a noise, autism. You might look at that and think, 'What are they doing at Brainvolts?' But really, the overarching umbrella is sound and the brain.

Just by looking at that list, all those different topics, you can see how many aspects of our lives sound is a powerful, powerful part of, and indeed we don't recognize it.

Russ Roberts: One of the things you talk about in the beginning of the book is just the mechanism of sound. I know I have an ear drum and I know there's a couple of other things in there--been in a doctor's office where there's a model of the ear and you go, 'Oh yeah, there's a lot going on there.' It's kind of extraordinary. We're not going to go into it in depth. But, the part that I thought was particularly interesting is that the brain moves very quickly and it has to convert moving molecules of air pressure into electric signals. Kind of extraordinary.

Nina Kraus: Yeah. It's marvelous. The process fills me with awe. So, the first part of the book--and it's just the first third--and it's called "How Sound Works." And, I feel like a little kid sometimes. You know how little kids like to read the same book again, and again, and again? They want to hear the same story. I have heard, I have told the story of sound, how sound works from a biological standpoint many, many times, and I want to hear it again. I want to hear it again and again and again.

But, basically, sound is the movement of air; and we have sound waves and we have brain waves; and the sound waves are air and the brain waves are electricity. And electricity is the currency of the nervous system. So, this transformation needs to happen. And, so much of what happens, not only it enters the ear, but it's really the brain that makes a lot of sense of the sound.

But, now, if we just think about: so what makes up sound? Again, visually nobody has difficulty. I've got this visual object and it's got a shape, a size, a weight, a color, texture. It has ingredients.

Well, sound, if you even pay attention to sound at all, sound also is rich with ingredients. It has pitch, timbre, harmonics, phase, how loud it is. There are many, many--how fast. There's so many timing, rhythmic cues. And, the brain, our sonic brain, our sound-mind, our hearing brain needs to make sense of all of these ingredients.

And, one of the metaphors that I use in the book is a mixing board. So, there are all of these different ingredients in sound. And, if you think of the faders of a mixing board going up and down, and each fader reflecting the brain's processing of one of these ingredients, we can see how good a job our brain is doing at processing these different ingredients in sound. And, not only does this processing occur in a very interactive manner, but it matters what our life in sound has been. So, these faders really reflect who we are in terms of our life in sound.

Russ Roberts: We tend not to think that, right? We tend to think like, 'Well, we all heard the same sound, so it's the same.' But, of course, we also think we see the same thing. And, of course we don't. Our brain is constantly interpreting what we see and literally editing things out. And, that's true in sound as well, as I learned from this book. We know that very directly because people say, 'Aren't you listening?' And, you go, 'What do you mean?' 'What?' Of course, your ears were taking in the sound, but your brain decided to just kind of not take it in.


Russ Roberts: One of the examples of this that I thought was so extraordinary--it's a very small thing, but I loved it--is the difference between 'bill' with a 'B' as in boy and 'pill' with a 'P'. Your mouth is doing the same thing. What's the difference between bill and pill that allows you to hear that difference?

Nina Kraus: It's timing. So, timing is one of my favorite and also important ingredients. The difference between bill and pill is the amount of time that it takes between the onset of the movement of the mouth and then the vocalization. So, bill, pill: it's a 30-millisecond timing difference that even though the motions that you're making are the same, there is a very, very clear acoustic difference. If you're a signals man like me, and you measure these brain responses, you can see as clear as day that there's a 30-millisecond timing difference between the onset of the voice in bill and in pill.

Russ Roberts: So, B and P--I'm trying to say P carefully not to pop my mic, my microphone--B and P are not really a vocalization. We have to get to the I, the '-ill', which are the B and the P there. After the P, I make a tiny unconscious hesitation when I want to say the letter P. Correct?

Nina Kraus: Yeah. And, then there are languages like in Hindi, for example, and Armenian--there is something called pre-voiced. So, you voice 'mmp', 'mmb'. And, that's something that our English-speaking ear or brain does not pick up. And, we can be trained to hear those differences--but again, a beautiful example, I think of how our sound mind is a product of our experiences. When we're born, babies--they're citizens of all the world's languages. They can hear any of the sounds, but based on what is meaningful to us.

So, if we grow up in speaking a language where pre-voicing is meaningful, or in Mandarin, where these tone changes within a syllable are meaningful, well, then our brain is going to change fundamentally, to the point that, when we are asleep and you measure the brain's response to these vocalizations, to these particular sounds, just depending on who you are, if you have made repeated sound-to-meaning connections with certain sounds, in your sleep, your brain will respond to that. And, it won't, if you are presented with sounds that you haven't learned to make any kind of a meaningful association with.

Russ Roberts: So, I'm living in Israel right now. I moved here four months ago. I came here with a rudimentary Hebrew vocabulary and I can read the Hebrew letters. And, Hebrew is a very impossible language. But, of course I'm 67 and many languages would be hard for me. Now, French would be a little easier or Spanish. I know them each a little bit. But Hebrew, of course, is not from the same root as English. But, of course, in my mind--well, English iseasy, because I know it; and Hebrew is hard because it's not like English.

I was fascinated by this data point you gave us that there are 40 or so sounds in English. Forty. I assume a sound is 'ee', 'ih', 'eh', 'ah'. My name in Hebrew is Russ. There's no 'uh' in Hebrew. So, people have trouble with my name. I happen to have a Hebrew name, as a Jew, which is Reuven, which they're very good at, but they're not so good at 'Russ'. So, there's 40 sounds in English and those are represented by a mere 1,120 different letter combinations, according to your book. As opposed to Italian, which has 25 sounds and 33 different letters.

So, English has 40-ish, roughly, times more combinations of letters to read[?] all those sounds. It's unimaginable that people come to America from a foreign country and learn English. It's such a hard language.

Nina Kraus: Yeah. But in fact, our sound mind--our hearing brain--is so miraculous in that we learn how to make sense of these sounds. And, one of the stories in my book is the owl story that is relevant, I think, to what you're saying about being an older person and starting to learn a language later in life. One of the things that you can do in an animal model is go directly and measure electrical activity from individual neurons. And, you can see--okay, so owls are nocturnal predators and so they really depend on sound. They found that you can change the owl's auditory and visual fields and you can actually see it reflected in the mapping of the neural activity in the brain. And, they saw this initially in younger animals and they were wondering, 'Well, is this something that an older animal can do?'

And, the first experiment that they did, they found, No: in fact, the older animal couldn't learn a new auditory visual space. What they do with these owls is they put psychedelic prisms on them that shift the visual field to the right or to the left. And so, you have to learn to make new associations.

But, then the scientists had an idea and they said, 'Well, maybe the older animals just are learning in a different way.' So, they used a different strategy. And what they did is they made the changes in the visual fields and in the auditory visual connections smaller.

And, over the same amount of time it took the younger animals to learn this new task and for their brain to get rewired in a way that you could physically measure it and see it, the older animals could do that, too.

So, that's telling us [inaudible 00:14:37] the older brain--and we know this just from so much converging evidence--the older brain, our brain is malleable until we die. And, of course we are different now than when we were four or five years old, or two or three. So, maybe we need a different strategy for learning. And, that's fascinating to me.

Russ Roberts: I guess that's a little bit of a comfort. My wife is studying daily her Hebrew. I don't have time unfortunately, but she goes to what's called an ulpan, where you study Hebrew--you start learning three hours a day and then she has homework and she studies grammar and everything. My view is that's not going to help me. I have to listen and speak. I'm not going to study anything. I'm not going to read charts or read rules.

I don't know if that's going to be true or not. What I do know is that for 10 years, I took French--third grade through 12th grade--and learned almost nothing. So, I'm hopeful. I'm hoping that I can do with a little bit better here. But you can teach an old dog new tricks, I'm hoping.

Nina Kraus: But, also you and your wife are different; and you hear the brain differently. One of the things that we discovered at Brainvolts is you can take a sound wave and we can listen to it. And, then using scalp electrodes, we can measure the electricity that happens in response to sound. So, as I'm talking to you now, the neurons in your brain are producing electricity. And we can pick that up. And, we can determine then that your wife, and you, and me hearing the same sound is going to--so the sound is the same--but the brain response is going to be different and you can see it in the electrical wave form.

We can even hear it because you can sonify the electrical signal and you can hear that your brain and your wife's brain are hearing the same sound differently. So, you're also going to learn--your way of learning through sound is going to be very different.

Russ Roberts: I can't help but add that George Steiner, the essayist and writer, has written an extraordinary book called After Babel--a reference to the Tower of Babel and different languages--where he argues that all language is translation. You and I process the sound differently, of course, as you point out, but the words mean different things to us, too. And we think we understand--we understand that we don't understand Shakespeare very well, but we think we understand Jane Austin because she uses modern English. But, Steiner shows that actually the words have evolved since then. And, what you hear versus a contemporary verse[?], not the same thing.


Russ Roberts: The thing I really liked about the owls in your book is that an owl--tell the example about the football field. That just blew me away.

Nina Kraus: Oh. Well, just an owl--and I'm not remembering exactly what the--you know, owls are just remarkable. Again, this gets to a philosophical issue of: we often think philosophically in terms of them and us. So, us being humans and them being animals and plants. And, plants and animals have extraordinary, extraordinary abilities that we are just beginning to understand a little bit. But, to put that in context with the owl: I can be at one end of a football field and you can be at the other and can snap my finger on one hand and the other hand, and the owl can resolve that difference, that spatial difference--it's a phase difference--very, very well. We certainly couldn't.

Russ Roberts: So, the owl is 100 yards away and I snap my fingers on my right hand, and the owl knows it's my right hand, not my left hand--not by seeing it. Even wearing the goggles--the owl is not going to be able to cheat. But it's going to know from--its eye is going to move toward the hand thats snapped, as opposed--

Nina Kraus: Absolutely.

Russ Roberts: Which is--a few weeks ago, we had an episode about dogs' ability to smell. I love this one. I just want to mention: there's a Robert Penn Warren poem called the "Heart of the Backlog," which has a very powerful and dark reference to owls' hearing; and we'll put a link up to that.

Let's talk about songbirds, because we're on birds. I just want to be clear: it's only a small part of the book on owls, about a page and a half. There is a chapter on songbirds toward the end, but it was one of my favorite chapters. Why does a person, an auditory neuroscientist, care about songbirds?

Nina Kraus: Well, first of all, they're beautiful. They're beautiful to listen to; and historically people have listened for birds to determine where to settle, because it turns out that places that are friendly to birds and to the survival of birds are often also friendly to humans. So, this has been a force that has been driving us.

Birds are fascinating from a number of standpoints. And, again, they help us understand human hearing, because we're able, again, to do various experiments with a bird that you can't do with a human.

For example, I mean, what we do know is that birds learn their song. They learn their songs from a tutor--from their father. And, you also need to know that with birds, it's the males that sing, and it's the females that choose. So, the male bird learns his song from his father. And, there are all kinds of things that you can get into in terms of dialects and what--the lady bird is going to prefer the bird with the closest dialect. She's also going to prefer the song that is most intricate, that has some nice improvisations, but that there's strength there because it's really a measure of fitness.

And, I also want to say that part of our research has been looking at sex differences in hearing. And, there are some; and it's kind of interesting to see this in the animal kingdom, because the male bird has a different job than the female bird.

So, the way that a bird learns from his daddy is that he imitates. He imitates the song. And, there are not very many species that imitate; and humans are one of them. Chimpanzees don't. People have tried to get them to vocally imitate.

Your dog can understand if you want to go outside. He'll understand certain words. But, if you're talking to your kid and you're saying, 'I'm going outside,' the kid will say, 'outside'; and your dog is never going to do that. And, this has to do with the fact that birds are vocal learners. We--humans--are vocal learners. And, it seems to be also attached to a very fundamental thing that humans do, which is--and birds--is that we're very sensitive to rhythms in sound. A human baby will move in sync with the beat of a song.

And, certain birds' song--certain birds--will also move in the same way. But, again, your dog is not going to be wagging his tail in time with the beat.

So, the fact is, and this brings me this issue of reciprocity and between this as McGilchrist talks about it--you know, this idea of back and forth of what you're hearing and what you're perceiving, and then you're adjusting what you're saying and your movements and what you're thinking--in the present--to interact beautifully with your environment.

So, birds give us a glimpse of this because they are one of few species that are vocal learners. They know how to imitate, and they can move rhythmically.

Russ Roberts: That's really beautiful, and I really love of the idea of the--I mean, I find birdsong, especially in the morning, very emotionally powerful. And I don't know--I love the idea that it could be part of my evolutionary past. And, I think that it's--it's 'comforting,' is the word I would use. Right? The idea that it's tied to a friendly, fertile environment that we evolve to appreciate that is a fascinating idea.

It also reminds me, though, that I think it's part of my childhood. So, it doesn't just evoke maybe my evolutionary past: It maybe evokes a time when I was a young boy. And, I had a certain feeling about waking up and being excited. And the birdsong taps into that, somewhat in the way that the music from my childhood has a certain comforting and belovedness to it that--I think, often, that we love the music we grew up with, not because it was particularly good: it just happened to be the soundtrack of our lives at that point. And, it's not obvious to me that the music that Baby Boomers grew up with, like me, is going to still be popular in 50 years because people then will have grown up with different things.

But, that birdsong idea, and the rise and fall of it, the melodic part of it, the rhythmical part--it's a musical element to life that I think we often don't notice, and I really appreciated noticing in your book.

Nina Kraus: Yeah. I think that one of the things that we may have noticed when we were in lockdown is that we were noticing the birds not only because there was less noise, but actually people who measured these responses from birds found that the birds were singing more quietly. The birds were singing more quietly because birds have to scream to be heard over the noise. So, they were not only singing more quietly, but they were singing more intricate songs--you know, intricate in terms of pitch and timing and timbre. The things that excite the lady birds. They had the energy to do that because weren't shouting above the din.


Russ Roberts: Well, we understand that because of what you identify as the cocktail-party effect. So, if I'm at a cocktail party and we're yelling because it's a noisy room--the acoustics of the room, or a restaurant, which happens--it totally changes the range of things you can communicate. Because, you've got to be loud, period. You can't be quiet. Talk about that challenge for our hearing system and the listening part of it.

Nina Kraus: Yeah. And, you can't be nuanced, either, because there is so much nuance in the sound. I started the episode--you know, you welcomed me to EconTalk and I know you could hear from the sound of my voice that I was happy to be there. And so, there is this nuance that you would completely lose in a noisy room where you're just trying to get the message across.

And again, I don't think that I don't think that people notice and realize how important this is. And, again, part of my book is really trying to get people to realize that this is important: that communication and connection is important. And so that we should honor it. But, we learn throughout our lives.

So, for example, you talked about memory and memories for songs. Well, in a noisy place, you will be able to hear your wife better than a stranger because you know something about the rhythm of her voice and you can pick up cues that--they do have--you've just learned. And you know, when you're in a room, depending on the music that's playing, it will affect you or not.

But, we, you know, we learn because we--you know, the sound enters our ear into our brain, and there we have this confluence, this engagement of what we call the efferent system, which is more massive than the pathways that are going upstairs from the ear to the brain. And, with evolution, these are more and more evolved. And, with our life and sound, our hearing, our actual hearing is sculpted not only by the sounds, but what is happening at the same time.

So, how we are moving. What we are thinking about. What we are feeling. And, the information from our other senses.

Again, this philosophically has to do with a binding problem. And, when you look at the sonic mind, when you look at the sound mind, the hearing brain, you see that these operations are--this is a reverberating circuit. And, you know, scientists like to  compartmentalize. But this is a distributed, but very interactive process.

Russ Roberts: It's a broad--it's an incredible network which I started to appreciate from reading your book. But, the challenge of hearing multiple voices at the same time and only listening to one of them is quite an achievement, right? Isn't that what--with the background noise going, too--

Nina Kraus: Yes. It is an achievement because--but again, we need to learn what to pay attention to, and we need to learn what to ignore.

So, again, if you are a speaker of multiple languages, it turns out you're particularly good at, they call it 'inhibitory control'--that you're pretty good at ignoring information and sounds that are irrelevant so that that particular part of your sound mind is going to affect how you hear a noise.

Russ Roberts: That's interesting. What's the McGurk effect and why is it important?

Nina Kraus: Well, the McGurk effect is--it just shows that our visual and auditory information affect each other. It's a very obvious demonstration. I do this in my classroom all the time. I'll ask somebody to just be saying the same sound like 'ba, ba, ba, ba,' and they're going to time it with the movement of my lips. So, I will be in front of the class and I will make the 'ba, ba, ba' movement. And, then every now and then I will make my mouth go in a position like F for 'fa.' 'Fa, fa.' So, they're either seeing 'ba' or 'fa.' So, they're seeing two different things.

As they see these two different things, they actually hear different things. I'll ask them, 'Well, what did you hear?' And, people will say: Well, there were some 'ba's and some 'fa's and some 'va's.

So, the visual information clearly affects how we hear the sound.

Russ Roberts: But you weren't making any noise. You're just making the face.

Nina Kraus: No. I'm just making the face.

Russ Roberts: They were hearing someone they can't see make just 'ba', but they would hear 'fa' even though--right? That's what happened, right? It's incredible.

Nina Kraus: That's exactly what happened. Yep.


Russ Roberts: Let's talk about noise for a little bit--maybe for a lot. As I get older, I find noise more annoying, meaning things I'm hearing I don't want to hear, particularly. You talk about the phenomenon where a truck will be idling on the street: It's incredibly loud, by the way. And we're walking along, and then it will stop--it might be idling outside your window; it stops. And all of a sudden, you give a sigh of relief, you write. We're like, 'Oh, right.' You weren't hearing it--but you were. It was going in.

I think about it with leaf blowers. When I lived in suburban Maryland, any afternoon in the fall was--they're so loud. It starts to affect more than just 'That's a loud noise.' It starts to make you feel--not feel so well. I don't mean sick, but it jars on you.

But, the example you shared with me in an email I want to focus on is beeping trucks, which I also find hard to listen to these days. And, especially as I get older. Part of it's because it's just beeping. Part of it is it's a really loud beep. In a good cause: keeps people from being run over, is the idea. But, talk to me about beeping trucks.

Nina Kraus: Yeah. Well, you know, beeping trucks are--there are so many times when--does every truck that backs up--every little van--many cars have this. You know? And, I really--it's not so much a matter of the beeping trucks as much as the whole idea of a soundscape and what we are so cavalier about.

So, I want to make the distinction between dangerous sounds to our ears--so, the sounds that are loud enough that will create hearing loss; and, everyone knows about that. But I'm really talking about--you're talking about the leaf blower that you can hear three blocks away--and it excites us in a not-so-good manner.

And, why does it excite us? It's because sound is one of our most evolutionary ancient senses. And, sound cues us about, 'Is this sound going to eat me? Can I eat it? Can I mate with it?' These are very deeply ingrained parts of our survival.

And we've all had that experience even in the night where you hear a sound and you're jarred by it. And, then you realize, 'Oh yes, this is a familiar'--the sump pump turning on, or something that you know.

So, we learn about this. But I think we don't even notice it. Again, like when I'm in the kitchen and suddenly the refrigerator turns off and I didn't know it was on and I'll breathe the sigh of relief, because I think that part of what disconnects us as a society and is, you know, part of the depression and mental illness that you had in the Lost Connections--

Russ Roberts: Johann Hari--

Nina Kraus: book, right?

Russ Roberts: Mm-hmm.

Nina Kraus: So, we just are in a constant state of alarm. We don't know it, but we are in this constant state of alarm and tension. And, it's just happened. Noise is just a byproduct of our industrial society. And nobody has really thought about it.

And so, what I'm hoping is that, with this book, people will think about how important, how deeply important sound is, so that we, as a society, can make better choices. So, to help us not be in such a state of tension and alarm, because our ancient evolution has primed us to be really aware of sound whether we're consciously aware of it or not. Our brain knows.


Russ Roberts: It's a really deep idea. It's the flip side of the songbird. The songbird, you don't listen to it. You might not be paying attention, but it's comforting you because it's tapping into something deep in your brain. The leaf blower and the beeping truck is agitating you without you realizing it. And, that sigh of relief when the noise dissipates or disappears is a measure of how agitated you were without your conscious knowledge.

It's a beautiful example to the Coase Theorem. But, the Coase Theorem, this idea that we interact with each other in intricate and responsive ways--so, if you have beeping trucks, you don't have to spend so much time worrying about trucks backing up when you're walking in an urban environment. I live in an urban environment now and a beeping truck is going to, besides agitate me when I'm not that close to it. If I am close to it, it's going to make me jump.

And I know that it's going to protect me. If the trucks didn't beep, the world would be quieter. And you might say, 'Yeah, but more people are going to go run over it.' Well, maybe, but you'll also have more people paying attention when they're walking. For better or for worse. And, that's the Coase insight: that, it takes two to tango. That things that affect one person yield a response that isn't just the fact that the noise is there or that you can be careful: It changes your behavior.

And I think--I wish my neighbor was a little quieter. We have a--I always wonder if there's a person outside who decides to go through my garbage, empty it, and then put it back in. It's actually just the garbage truck picking up the can. But that's an unbelievably loud noise in most urban environments. The garbage truck has all this internal mechanisms to crush the garbage, and at 4:30, 5:30 in the morning where I'm living now, he's out. I'm glad he picks up the garbage, by the way. I'm really glad. But, it is a--it sometimes wakes me up and I wake up with anxiety. So, it is a great insight.

Nina Kraus: Yeah. But, Russ, so you talk about beeping trucks and the two sides of it, right? And, my students are always furious with me because they always want to have the answer.

Russ Roberts: Yeah, of course.

Nina Kraus: And, my answer is, generally: It depends.

Russ Roberts: Yeah. Trained like an economist.

Nina Kraus: I'm really wanting--people--if you're aware of sound, then you can do certain things to--you have some control over your own sonic environment. And, you can help in making decisions for our classrooms.

I actually, I mean, we know that it is harder for kids to learn in a noisier place. Again, they can hear the teacher, but they're learning because learning is disrupted when there is this moderate level called 'safe noise', safe level of noise. But it has a deep effect on us.

So, I am hoping that--and I give many, many examples in the book that people can think about with respect to their own lives. I like to give personal examples because, again, science is a deeply human endeavor and it's performed by humans. Science--a book about the biology of hearing in our lives is written by a human and what is really important. Again, and here we talk about the tyranny of metrics. You know, in science, we are so limited by what we can measure and we often forget and we don't appreciate all the other forces.

So, for example, wisdom is one of these things. If you go to a conference on aging, anything you can measure--like, how fast it takes me to put the key in the door, I mean, I'm slower at this than I was when I was balancing a kid and groceries and getting the key in really quickly. So, anything you can measure, as you get older, it gets worse. But, you can't measure wisdom and there is--clearly, as I say in the aging chapter, I am so happy as an older person. And, I feel like I understand--I have an appreciation of the world in a way that I didn't have before.

And also with making music. There are so many things that you can't measure, like the self-esteem that a kid gets from performing on stage and interacting with people he otherwise wouldn't interact with.

Russ Roberts: Yeah. It's also though the insecurity that arises from giving a horrible recital.


Russ Roberts: I want to talk a little bit about music because I know it's an incredible passion of yours. All of our kids, I think, had piano lessons. One may have had a guitar. And none of them stuck with it. They all love music, but none of them stuck with their lessons. I self-taught. I was given no[?] music lessons growing up. I self-taught myself self-guitar in high school, and played it for a long time with some various levels of seriousness. And now I haven't touched my guitar in forever, but I did bring it with me to Israel even with--sorry, it's in storage. But, it's funny. It's in my mind, it's in the corner of my room. It's not it's sitting in storage in Maryland still, because we haven't brought our stuff yet. But, all our kids got music lessons.

And, I think it's tempting to say, and I would've said until I read your book that, 'Okay, I was trying to get them a love of music. Maybe it helped.' But, I was also kind of enjoying the idea of them having an instrument to play, which is a beautiful thing to have--for thousand reasons. And it just didn't work out.

But, you suggest in your book, quite passionately, that learning to play an instrument--and you include singing--learning to play an instrument has vast impact beyond the instrument that sticks with us for a long time. So, give us an overview of that.

Nina Kraus: Yeah. So, good job, Russ. You did the right thing in giving your kids music lessons. Because, often people say, 'Well, my kid is not going to be a professional musician.' And in fact, there are very few professional musicians. But we are all musical. We are all musical--and what we learn early on--so, we've done studies across the lifespan, but especially in older adults--actually, when I give a talk, I often ask the audience, 'How many of you have had a music lesson at some time in your life?' Every hand goes up. And then I ask, 'Well, what about now?' And, not that many.

But, the fact is that we have been able to measure in terms of how well the brain processes, the ingredients of sound that are important for language as well as music: If you have early experience, or if you have experience really at any time of your life, playing a musical instrument, making some kind of music--and, yes, of course, voice is a wonderful instrument. But, if you are adjusting the physical complexities of your body as you're hearing and moving and thinking and remembering, paying attention, coordinating with visual information--and this is so important for so many other activities.

But, again, objectively in these older adults, we just simply divided them into people who had played a musical instrument at one point in their lives--you know, four or five years in band or something like that. And, then it was 40 years between then and when we measured their brain responses. The people who had played a musical instrument earlier in their lives had a sound mind that reflected the processing of sound details that are very important.

And, are especially important for what you brought up, Russ is: hearing a noise.

And, hearing a noise is something that does get worse. It's difficult for everybody. But, it gets more difficult as we get older. But, being able to--that history of having played a musical instrument has a legacy. And, again, we can see it objectively in the brain responses, which I find so beautiful--to be able to think about something as complex as communicating in a noisy environment, and then to be able to actually see the differences that people's experience with musical education has on the older brain. That's remarkable.

Russ Roberts: I agree. Although, if I had not read your book and you told me that, I would've said, 'Well, that could just be what we call selection bias in economics.' Not a random sample. The people were giving music and lessons when they were younger, were different, came from kinds of homes. And, that could be true. And, I'm sure that would complicate trying to measure it with any precision.

But, what I want to say is, is that reading your book gave me the possibility that it could be true. I would've dismissed it. 'Oh, come on.' Because I played the violin.

But, what your book does is illuminate these connections between the brain and sound that I just had never thought about.


Russ Roberts: One of the things you say in there, which--I want to make sure I get this right--many people who cannot see have unusually developed hearing and musical ability. And, I always thought, 'Okay, it's a sort of a compensation. It's just a different draw from the urn.' And, again, there's a selection bias: We happen to--we know about Stevie Wonder because he writes amazing songs and he's incredibly talented. So, of course it makes us maybe think that some people who have missed one sense, get an extra sense in the other.

But, what you show in the book--tell me if I got this right--that the brain changes if you can't see. Once you can't see, the parts of your brain that were used for sight now get gobbled up by sound. And, there's sort of this imperialist thing going on there. Did I understand that correctly?

Nina Kraus: You are so correct. And, it fills me with relief and gratitude, that you got this from the book. Because, this is why it matters what we do. We have a responsibility for how we spend our life in sound. We have a responsibility for our children, for our educational system, for our city planning. We have a responsibility. And, the reason, or the reason I get as a biologist can talk about easily and with strength is that our experience with sound changes our brain.

It changes, biologically, who we are. Because, we are our memories; and our memories are very much what we hear, what we have heard. And, so, you know, we and our children are shaped by our life in sound; and this is important. Yes, because it shapes, it changes our brain.

So, we have--this is a call to action. We have a responsibility to ourselves and others to give this a think.

Russ Roberts: Well, to give your book probably the highest praise I can--again, if you haven't read the book and you're listening to Nina, you might think someone's crazy. You know? I mean, it sounds nice and it's great to hear, and 'I'm glad I'm not deaf.' Blah, blah, blah.

But, the book really does make it an interesting and persuasive argument that sound is more than just hearing. And I think that's the simplest way to get someone interested in these ideas. Because, all my life I thought, 'Well, sound is hearing.'

I'll give you an example, actually, that you talk about in the book and let you give me a hard time. I mentioned earlier that my left ear is not quite great. I think it was damaged during a time when there was construction outside my office when I was a professor and--a normal professor anyway. And, I put in headphones and cranked up music really loudly for months to be able to work above the din of the noise. So, I heard a different kind of noise that I liked.

And, I think I damaged my hearing in that period. It could have been I got a cold. I don't know what it was. But, anyway, my left ear doesn't work very well. And my right is okay, but it's not it's not what it was.

So, I have to ask my wife to repeat stuff--which is cruel. We live in an apartment now that has really high ceilings and it's really echoey and it's hard to hear for me.

So, I thought about getting a hearing aid. You know? So, I go to the doctor and he says, 'You know, hearing loss is bad for your brain.' And, he said, 'People who have hearing loss and don't get hearing aids have less brain function.'

And I wanted to say--I didn't say, I don't think I said this--I wanted to say, 'Do you know who you're talking to?' Like, 'You're talking to the wrong guy. I know about correlation and causation. And, the fact that there's this correlation between people with hearing loss and some imperfect brain function is really complicated by income and all kinds of things. So, the people who choose to get hearing aids are not a random sample.' Etc., etc.

So, I'm comforting myself with this for why I didn't get that hearing aid. And I still don't have it. But after I read your book, I'm thinking about it. And, the reason is, is that you make the case in the book--oh, you know, he also told me, 'You know, when you can't hear, you feel left out.' And I said, 'I get that. I'm not at that point yet.' And I understand that if you don't talk to anybody--because you can't hear them and they don't want to talk to you because you're annoying because you can never hear them--yes, you get isolated and that affects you.

But, he was trying to make this case--this seemingly silly case--that it's going to affect your brain just not having your hearing, by itself. But, you make that argument and it's giving me pause. So, why is that connected?

Nina Kraus: Well, I mean, it's actually very much at the core of the book, Of the Sound Mind. The sound mind engages what we hear, how we think. So, how we think--our cognitive skills, our memory, and our attention; how we move; how we combine information from other senses; and how we hear.

Now, we know this from a biological perspective, because we can measure the activity of neurons in response to sounds that a person has a certain feeling about compared to one that they don't.

Or--I mean, there are so many. So, one of the things that you know, Russ is that 20% of the book is references. So, you know, for anybody out there who is listening and saying, 'Oh, she's just saying,' there is a lot of science and a lot of converging evidence that I felt responsible, as a scientist, to put there for anyone who--but even if you don't look at it, just to know, I'm not just saying. There are many: we know this from a biological perspective.

So, yes, if you don't hear as well, you are not going to be thinking as well, for a number of reasons. First of all, because hearing just automatically engages how we think.

But, also, because if you are putting effort into trying to figure out what I'm saying, you don't have that--they call it cognitive reserve--to be thinking about, 'Well, what is she saying?' from a theoretical standpoint. You're not just trying to get the words, you're trying to actually think about what I'm saying. And, your ability to do that is diminished.


Russ Roberts: But, isn't that inconsistent with a different claim you make? And, by the way, I think you know, Nina, that I don't like the phrase, 'Generally studies show.' But I would say that the studies in your book are different--many of them were different. They are things like what happens to this neuron. And I'm sure there are issues about reliability and replicability in this research, too; but it's not quite the same as what economists do. A lot of it was, I thought--seriously, it was very powerful.

But, when about the effort you have to take to hear when your hearing is imperfect, you'd have to pay attention. And it's tiring. It's physically tiring. You struggle. There's a limit to how long you can do. It's hard to focus, right? In general, it's just always a challenge; and focusing to hear is challenging.

But, I'm thinking about language acquisition. If I speak in Hebrew now with a native Hebrew speaker who is being nice to me and speaking slowly and correcting me when I'm making a mistake, and asks me questions, and we're going back and forth--it's not just me talking for the time and not just listening, but a conversation. It is totally exhausting. I can do it for about an hour. It's an enormous amount of time to do it. And yet, I think that's actually good for my brain. So, how do you reconcile that with the claim that, when I'm hard of hearing, it's bad for my brain?

Nina Kraus: So, it's going to depend, right? It's going to be important for you--I mean, anything that is worth--if you're going to change your brain, it is going to take a while to change your brain in a fundamental way, in the ways that we can really measure deeply and biologically, ways that are--your brain while you're asleep, while you're awake, that's fundamentally you. And, for example, we found in our studies in schools where we looked at music education, that we didn't find changes after a year of music making: that it took two years.

So, we're really talking about ways in which you fundamentally change how you intersect with the world. So, if you are constantly, now, on a daily basis in sort of a dulled relationship with the world, your brain is going to change to the point that--you know, before you had the hearing loss, your brain would hear different elements in sound that would automatically help you think, and remember, and feel in ways that you weren't even aware of.

Russ Roberts: But, I think there's also a weirder piece to this, which is: I think being thrown into a language environment that is not your native tongue, and being thrown into an environment where you can't fully hear and you struggle, are very similar, right? And, what I've noticed--and I think this is maybe a different way to say what you're saying--what I've noticed is that--my joke is that when I hear a serious native Israeli speaking at full speed--Israelis speak very, very quickly, I think even for native Israelis, I think they speak quickly. And, my joke is it's like the bar scene in Star Wars, to me. It's like [Russ emits made-up words, spoken rapidly, high pitched] 'Mieh-pupito...'. It's just a bunch of noise. It's noise.

And, I might recognize one word and I'm going to struggle to separate the words because the spaces aren't there. When you speak in your native tongue, the spaces are all contextual: You know exactly where they are. You know what the words are; you don't get confused. But you're just hearing this foreign language.

And what I've noticed is that if I'm not careful, my brain just shuts down. It's something I noticed in my father before he passed away when his hearing was really deteriorating. He didn't want to wear his hearing aid. I could see he just kind of shut down.

And I always thought it was because he didn't like to hear and failed to hear and then have to ask. But, I think it's worse than that. I think it's just like your self-esteem is down--and that's true as the language learner and as the hearing-loss person--and your brain kind of says, 'I'm done. Too hard. I'm going to rest. I'm going to hear it as just a bunch of random noises like the creatures in the bar.' I don't know. That's the way I feel sometimes. Awkward.

Nina Kraus: Yeah. But, Russ, you are tuning your sound mind; and I really encourage you to learn another language because it takes effort. This is something that will take years, but it's a good kind of effort. To be putting in this kind of effort, what the result is, you are tuning your sound mind.

If you are putting a lot of effort into trying to hear without a hearing aid when you need one, you are dulling your sound mind, because you're not thinking and engaging and you're not as biologically engaged.

So, again, it depends. I would really encourage you, as I encourage--I think , educationally, learning another language of course gives us a lot of perspective in many ways. But, certainly from a sound standpoint: but as you continue to become more familiar with this language, which is around you, how wonderful! You have this opportunity, right there, to strengthen your sound mind.

Russ Roberts: Yeah. And when it happens, when it works--like, I hear a whole sentence--I get so excited. You do get a nice rush, thrill.


Russ Roberts: You mention in passing, and I don't think you said much about it, but you mention in passing that the brain is not like a computer. The brain as a computer is a very popular metaphor, and I've mentioned it on the program before--I think I got it from a former, a past EconTalk guest, Daniel Botkin--in one of his books, he traces the history of how we conceive of nature as whatever the most advanced machine is. That's our metaphor.

And, I think that's very much our nature or the way we look at the brain. The brain is like a clock. Now, it's like a computer. Personally, my suspicion is it's not, but I'm curious why you say that.

Nina Kraus: Yeah. I think it is so wrong to think about the brain as a computer, because it isn't a computer. Our brain works nothing like a computer.

Think about our daily life that is so run, not by humans, but by bots where you make a phone call and you have to say, 'Do you want this? Do you want this? Do you want this? Do you want this?' Because that's the way a computer works. Whereas a human being, you could tell them in a second, 'I want to know how to make my African violets grow,' and they'll know exactly where to send you so that you're not spending hours doing that.

You know--chess is often this example where computers will go through billions of possibilities, because that's how computers work.

A person who understands chess is going to maybe think of eight moves. And, again, just figure out what is the best move in the moment to make.

So, fundamentally, the brain is not a machine. It is an intricate biological system that is responsive in so many ways that we know about, but mostly all of the different ways we don't know about: all of the bacteria and RNA [Ribonucleic acid] that are in our cells that run our--what we think is heredity.

There are so many factors in our biology, that as biologists--I mean, I love being a biologist because we know a couple of things, and it's exciting to talk about these few things that we know, but I think it's really important to say we don't know--we don't know--how this works. Because it is so, as you would say, glorious. You like that?

Russ Roberts: I do.

Nina Kraus: And, it is glorious. And, there's so much there to understand. And, we know how computers work.

Russ Roberts: Yeah. That's a great point, by the way, in and of itself. Right? If you say the brain is a computer, it's strange that we don't understand it. Because, we really understand computers really well. That's a fascinating, simple observation. Do you think most neuroscientists agree with you?

Nina Kraus: No.

Russ Roberts: The mainstream view right now is that the brain, quote, "is like, is some kind of--"

Nina Kraus: Well, I think it, if there's much--

Russ Roberts: It's got on/off switches--

Nina Kraus: Yeah. And, also that we can see things. So, imaging is so--and everybody thinks that--not everybody. But, there is a view that if you can see what part of the brain is active or lights up, that that somehow tells us something.

I mean, yes, it gives us some--yes, it gives us some information in the converging-evidence, larger picture. But, people so often have this sense that there is an answer. 'Oh, this part of the brain is active.' And, by the way, with imaging, it isn't even neural activity. You're measuring blood flow. And, this part of the brain is active.

And so, 'Oh, now we understand what happens when we meditate.' Come on.

Anyway, that's my view.

And also: one of the reasons that, at least in terms of my essay--I like to look at physiology, which is--you know, it gives you a different kind of information. Again, it has its own limitations.

But, I think that scientists often are drawn by a modular and a visually biased view of how the brain works. And, that's really not my view. And it's a view, actually--if you think of the National Institutes of Health, there was a National Institute on vision, 13 years before there was one on hearing. But, just the fact that we have these National Institutes of different individual fields, is--it's helpful in some ways. But really, and again, as a biologist, I really think that Truth--the capital "T"--is when we get into the intersection of fields including, the--very much including philosophy--but different branches of science.

And this is not the way science really works, for the most part. It's not the way study sections work. It's not the way--you know, that you really are looked at by specialists in a particular area.

So, again, it's just this dance between understanding the intricacies of the fields that are relevant to a larger perspective.

Russ Roberts: Yeah. It's a recognition of the organic, emergent character of the brain, I think. And, therefore the multifaceted, multidisciplined, whatever you want to say about sentences in the brain--which again, I didn't fully appreciate until I read your book. It's kind of obvious once you think about it and see it that way, but it's not the way we always organize things.


Russ Roberts: Let's close by--I'm going to talk about what I got out of your book, and then I want you to take us home with anything you want to add at the end.

I really do think that most people think of sound and hearing as this standalone thing. It's like: if you're out in the rain, you get wet. And, with the noises, you hear them. I think that would summarize the way I thought about my sense of hearing and the role it plays in my life. I love music. I love trying to acquire a second language. I love the lilt of a great poet reading, a great reading of poetry or great orator. So, there's a lot of things that I like about sound.

But, the wholistic lessons that you provide in the book about how we choose to live--and, I mean, there's some small ones like you might want to wear earplugs more often--that's a nice, that's a good point to keep noise from battering us, battering you in your daily life.

But, I think the mix of thinking about music, language, conversation, and how the sense of hearing and the ear interacts with the brain in both directions is really--life changing, is a little strong. Obviously, it is for you, because it is your life. But, I think your attempt to make people aware of these processes and the awe that you have for it and the awe that you were able to convey in the book really is special.

And, we didn't talk about how we hear in any detail, but that alone is such an extraordinary and all that glorious part of being human that I just didn't appreciate.

So, I want to thank you for the book. And, I think it actually will change my life a little bit. I might get the hearing aid. I might be more dedicated to my Hebrew lessons. But, more importantly, perhaps, just more appreciative of how, what it is to be human and have these interactions. So, that's my takeaway. And, you can finish and add anything you want.

Nina Kraus: Yeah. So, Russ, you already know a lot more than you think you know, in that you spend a lot of your life in sound. You spend a lot of time interviewing people. And, this is done through sound. And, maybe you weren't quite aware of that.

But this is deep. Sound connects us. It connects us in the moment, in the present. It makes--and, what is so fun and you know why it's fun to talk with you is: I don't have a script. You don't have a script. We are everyday improvisers.

And, what's exciting is where we are connecting and moving together. We are--it's this reciprocity, this back and forth that happens through--I mean, sound is one of the few--because sound, it happens and then it's gone. But, while it's happening, it's happening. It's happening and it's connecting us and it's really--it's connecting you and me and our minds, so that in this time where I think there is increased isolation, and depression, and divisiveness, and alienation, I think sound connects us. And, for that reason, we really need to recognize the beauty, the power of sound in our lives.

Russ Roberts: My guest today has been Nina Kraus. Thanks for being part of EconTalk.

Nina Kraus: Thank you.