Dr. Nina Kraus

Neurobiologist and director of the Auditory Neuroscience Laboratory at Northwestern University
Headshot of a woman.
Photo courtesy of Dr Nina Kraus

Music Credit: “NY” composed and performed by Kosta T, from the cd, Soul Sand.

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Nina Kraus: Sound processing engages many systems in the brain. So it engages our emotional system, our reward system. It engages how we think, our cognitive system. It engages how we move.

Jo Reed: That was neurobiologist Nina Kraus and this is Art Works, the weekly podcast produced at the National Endowment for the Arts. I'm Josephine Reed.

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Sound is something most of us take for granted. You’re listening to the sound of my voice and you’re making sense of the words I say or that sound that I produce. Sound is one of the most complex tasks our brains do, and one of the main ways we learn about the world around us. Dr. Nina Kraus is a professor of neurobiology at Northwestern University where she directs the Auditory Neuroscience Laboratory, also known as Brainvolts. She has made the study of how we biologically process sound her life’s work. Dr. Kraus and the Brainvolts team formed multi-year partnerships with a number of Chicago Public schools and with the Harmony Project, an after-school program in LA that teaches music to children in low-income communities. They measured the brainwaves of the children and discovered that the act of making music can have a long-term impact on the brain and the way it processes sound.

Dr. Nina Kraus explains:

Nina Kraus: So with the Harmony Project, Margaret Martin, who is the founder of the project, where music is delivered after school from early in kids' lives through when they graduate in high school. And once they're in the project they get the music one year after another. And she has a Doctorate in Public Health and she has been tracking these kids and finding that in fact they do very, very well in the community, in school, in their lives, but she was wondering what is going on biologically. And since we measure, at Brainvolts we measure sound processing in the brain, we took part of our lab out to Los Angeles. Year after year we did this for three years and measured the brain's response in many of the children as they engaged in making music and as they engaged in their programs. And we watched how their brain response to sound changed year after year. We wondered would this be something that would be honed by music making and also since sound is such an important vehicle for language and learning happens through language and the other forms of communication happen through language, we wondered if there would be a connection between the neuroprocessing in the brain and the children's language abilities and their abilities to hear speech and noise and their abilities to pay attention. And in fact, we really were able to see very deep connections between changes in sound processing in the brain, which really did happen and how they tracked with their educational success.

Jo Reed: Well, many people spend a lot of time listening to music, but you have found that doesn't have the same biological impact as actually creating the music.

Nina Kraus: People often say, "Oh, I listen to music all the time. Music is a big part of my life. You know, if I listen to music all the time is that going to change my brain in the way that I talk about?" And I like to say, you know, you're not going to get physically fit watching sports. You actually have to do the activity, so you actually have to make the music, whether it's singing or playing an instrument, it is that actual making of music which is important.

Jo Reed: And it was interesting because studying it for one year, studying music for one year was not enough. You were not seeing those changes. It was after the second year that you could begin to track those changes. I was really struck by that.

Nina Kraus: Yeah. Yeah. Well, so were we. <laughs> And we also worked with a number of schools in the Chicago Public School System and so the idea was similar there, too. Would the kids who were regularly enrolled in music programs in the school, so they, there were some schools that had music as one of their regular subjects like English and Math, would the kids who played music, would their sound processing change? And again, we found that after a year we really did not see any fundamental changes in the way the brain processed sound, biological changes, because, you know, we measure, sound processing by using sensors that measure the electrical activity of the brain. And this activity eventually did change, but we only saw it after two years of music making and I think that really speaks to the fact that anything that has a real fundamental impact on who we are and what we become is often something that we spend a lot of time doing.

Jo Reed: Are you able to do a longitudinal study so that you can see how long those changes last? Let's say somebody studied music for five years and then as often happens, stops?

Nina Kraus: Yeah. Yeah, so we followed these individual children for a number of years. But we have also done many cross-sectional studies of people across the lifespan and especially we've been interested, you know, as we get older, often what does happen is people will have had music lessons at some time in their lives but then, you know, fast forward to today and it's been 20 years, 30 years, sometimes 40 years, and they haven't played their musical instrument. But the fact is, a little goes a long way and playing music for a number of years at any time earlier in one's life seems to have a lasting impact on how well, how good a job your brain does processing sound. So as an older adult, for example, one of the most common complaints is difficulty hearing in noisy environments. And we find that people who have had musical experience earlier in life, even if they're not continuing to play, will in fact have an easier time making sense of sound and hearing in noisy environments.

Jo Reed: You write about sound, the importance of pitch, of timing, of timbre, and of rhythm. Can you just walk us through, as easily as you can, how that is important to the way we learn and apprehend the world?

Nina Kraus: Absolutely. I love talking about this. You know, we live in a very visually dominated world and I think it's because when we look at an object we can see its qualities right away. We can see what is its color, its shape, its texture, its size. With sound, sound has just as many ingredients. So sound has pitch and timing and timbre and phase and loudness, rhythm. Sound is invisible. So we are often just not aware of what a powerful force sound is for us in our lives, what an incredibly powerful force sound is for changing and evolving our inner biology throughout our lives, really because sound is invisible so we are not conscious of its presence as much as we are with visual information and yet our nervous system is as conscious of sound as it is of anything. Actually, sound is one of the most evolutionarily ancient senses. There are no vertebrates that don't have a hearing apparatus and sound is what signals to an animal for survival. Is this danger? Should I stay? Should I go? Should I mate? Should I eat? So sound is this tremendously important biological force that it is just a wonder to investigate and to look at and to see how sound processing in the brain works in different people, each of us in the same way as we look differently, our brains process information. We see and hear the world differently based on a combination of our genetics and our experience.

Jo Reed: It's interesting because, well, obviously because I do podcasts, I'm aware of sound in a very different way than you, obviously. And I'm aware of sound being waves. And when we first moved into this studio, I would record and I would say, "The room is dead," because there had not been any sound being created. And I would play music in the room when I wasn't here so the walls could absorb those waves until, enough sound had been created in this room so that the room sounded less dead. Does that make sense to you? <laughs>

Nina Kraus: Yeah, yeah. Yeah. And so this is your own experience with this space.

Jo Reed: Yes.

Nina Kraus: Every space has a sound. You know, we don't really think about that necessarily, but, why are cathedrals such marvelous places? Because they deal with sound in a very special unique way. You know, when we look at ancient cave paintings, they were done, it turns out, in the most acoustically strong and interesting areas in the cave. So this would draw people to be where they then made their cave drawings. But you speak of your experience in this room and that is so fabulous, because we change depending on our experiences. And so this room will sound a certain way to the uninitiated, but to someone like you who has experienced this sound and really has a detailed appreciation for the nuances of the soundscape, that you know, I wouldn't have unless I've spent the time that you've spent in here, what's wonderful is that in fact your brain has changed in how it responds to this space. And I would bet that if I measured your brain's response just to a speech sound in this room years ago when you started, and measure now the brain's response to the same sound, you would be processing it differently. You would be pulling out different ingredients that you have now found to be pleasing and useful to you.

Jo Reed: That's fascinating.

Nina Kraus: Isn't it fascinating?

Jo Reed: Yeah, completely.

Nina Kraus: Yeah. And I do love-- I love podcasts and I love listening to books. I love listening, of course, to sound. And, you know, what a great way, what a great platform to talk about sound through sound.

Jo Reed: We talked about the children and learning and children who study music, their brain processes sound differently and it carries over, tracks into their learning. Can you explain a little bit how you think that might occur?

Nina Kraus: Yeah. So when you're listening to somebody, say a teacher, you need to be able to make sound to meaning connections. You need to be able to connect the words that are said to the meaning and so the better you are at that, the better you are able to make sense of what is being said to you. Let me give you an example about auditory working memory. So auditory working memory, if I were to test you, I'd give you a list of words and then ask you to repeat, "Tell me of the words that I spoke, which ones are the names of flowers that begin with the letter 'G?'" So you have to think, okay, which ones were flowers, which ones start with "G?" So you're working your memory. Auditory working memory is very important in making sense of what is being said at the moment, so right now you are following what I'm saying. You're following the conversation because you remember what I just said a few milliseconds ago. So your auditory working memory is really important for that. Now you can imagine as a musician, anyone who is making music, you're constantly needing to remember a passage and then playing it and then remembering and you're strengthening that auditory working memory that is inherently a part of making music. And you can see how it would spill over into other times that you process sound, like in a classroom.

Jo Reed: You talked about when we get older our sound processing begins to diminish. But you also looked at musicians and given this conversation the finding will not be surprising, but please share it anyway.

Nina Kraus: Yeah. Well, so we looked at the sound processing of individual ingredients. So in particular, as we get older, the brain's ability to process the harmonics, which give us information of the timbre of sounds, that often diminishes. That just the timing of neurons, especially when the sounds are very rapid, that the timing can slow down, the response of the brain can be less consistent. So I can say a word to you and if you're an older person, I can repeat that word and your nervous system will have a jitter in how it processes each word even though, you know, I can say it in identically the same way. And also this notion of neurons firing together in synchrony, this is something that weakens as we age. But older adult musicians have responses to sound that really are indistinguishable to responses of a younger person. So you really see this strong sound processing in the brain that seems to be a consequence of having engaged with sound in making music for one's life.

Jo Reed: And what about rhythm? I know you're beginning to do work on rhythm and that just fascinates me. Tell me what you're doing.

Nina Kraus: So rhythm, you know, we all think of rhythm as being a part of music, but rhythm is also a part of speech. And as we speak, there is a rhythm, there's a cadence in how we speak to impart meaning. And it's been known for some time that children, for example, who have difficulty parsing certain rhythms and producing certain rhythms can have difficulty with language. But we also know that following rhythm, and especially the rhythm in speech, can help us fill in the gaps in noise. When it's noisy, we can follow where we expect that rhythm to be. So by following sound over a long, a longish window of time, we can imagine what the sounds are going to be, even though we have incomplete information if we're good at processing the rhythm of sound. And so, it's not a surprise that engaging in rhythm activities whether it's with music--we've been working with a program called Interactive Metronome, where engaging in these rhythmic activities makes you better at rhythm. But what we of course are interested in is not only being good at these rhythm tasks but also being good at making sense of the sounds that are in our environment and being able to pay attention to what's important and being able to ignore what's not important.

Jo Reed: You and the Brain Volts team have been really involved in looking at sound processing in the brains of people who have sustained concussions. I’m curious about the connection between sound processing in the brain and concussions.

Nina Kraus: Well, making sense of sound is one of the hardest jobs that we ask our brain to do. We have to process sound on the order of microseconds. This microsecond precision processing is faster than the processing that is required, let's say, for processing visual information. It's one of the hardest jobs our brain has to do. So getting hit in the head, you can imagine, might disrupt this mechanism. And people are using the visual system and the balance system as indices of health in concussion. But now, there has been some attention paid to processing sound and processing sound in the brain. And it turns out that sound processing in the brain can be disrupted by a concussion. So we're engaged at the moment in a study, where we are testing all of the Northwestern Division 1 athletes and test them both as healthy athletes and if they sustain a concussion. We are very interested at to develop the idea of looking at rhythm training following a concussion because most concussions will resolve after about a week, but about a third of the cases, people continue to have symptoms. And so they have a difficult time returning to play, returning to learn, and can we speed that recovery through rhythm training?

Jo Reed: Have you done any work about literacy, about like children who are developmentally slow in reading and how that tracks to sound processing?

Nina Kraus: Oh, yes. We've done a lot of work with individuals who have difficulty with language with respect to being language delayed or having difficulty reading. And we really can see that their sound processing is often disrupted. So you know, you might wonder, well, you know, what does hearing sound have to do with reading? But of course when you're reading, you're needing to associate the sound of the letters with the words on the page and the letters. So again, there has been a lot of research showing that sound processing is important for language skills and we have been able to show this biologically and to actually be able to show that biologically some of the ingredients that are diminished in children who have language disorders, who may have been linguistically deprived, especially in low income areas. You may have heard of the 30 million word gap. That is where kids whose moms have less education are thought to hear 30 million fewer words than kids whose moms have more education. And that's often used as a proxy for socioeconomic status and for poverty. And what we did is we measured the brain's response to sound in the same classroom in children who were simply divided based on how much education their mothers had had. So these are, you know, kids educated in the same school, same classroom, same low income area. And the kids whose moms had more education had brain responses to sound that were more accurate and precise than the kids whose moms had less education. And a very interesting point here is that we found that in the children whose moms had less education, they had more neural static, more neural noise. And interestingly, in the work that we have been doing with athletes, so our Division 1 athletes at Northwestern University—these are elite athletes. And we have compared their brain responses to 500 Northwestern students who are not on a team. And what we have found is that the brains of the athletes are especially quiet with respect to this meaningless static. So they have this low level of background noise which makes it more possible for them to process sounds, so that if there's a lot of commotion in your brain in terms of neural activity, it will make it harder to hear the signal. But in these athletes, we see that their signal processing is especially good. The athletes, who need to make a lot of sense of sound, of the--they have to hear the coach. They have to hear teammates.

Jo Reed: Well, baseball players say, "I could tell when the ball hit the bat that it was a homerun."

Nina Kraus: Exactly. It’s been exciting to be able to see, you know, playing sports is one of the best things that you can do for your health and to see that it has an impact on sound processing--

Jo Reed: Fascinating.

Nina Kraus: --is fascinating I think, too.

Jo Reed: Now, you've helped develop a test for young children that can flag future problems that they might have with reading.

Nina Kraus: Mm-hmm.

Jo Reed: Please explain that.

Nina Kraus: Yeah. So the measure, the biological measure that we use is the frequency following response or FFR. And this is a biological response to sound that can be obtained without any active participation on the part of the participant. So they can be sleeping, they can be watching a video. They don't have to be engaging in the task, which is great if you have a little kid who may not understand the instruction and you could just have him watch a video while you measure sound processing in his brain. And since we have very good norms, we know what the sound processing of the different ingredients of sound should be for a given age and sex. And if the child's response falls outside of these norms in a number of dimensions, that tells us, well, this is a child who is at risk for a language problem. Wouldn't it be wonderful to be able to track the kids before they actually have difficulty reading? You know, so in other words, if you can tell at 3 that, oh, this is a child who is likely to be at risk for developing language skills and developing reading, wouldn't it be great to right away--

Jo Reed: Get them in a music program. <laughs>

Nina Kraus: Get them in a music program and intervene because, again, we are what we do.

Jo Reed: Okay. How did you get in this business?

Nina Kraus: Well, my mommy was a pianist. I liked to play underneath the piano when I was a little girl. And--

Jo Reed: Can we just say a word. My brother plays the piano.

Nina Kraus: Yeah.

Jo Reed: And being underneath the piano is wonderful because you feel the music as well as hear it.

Nina Kraus: Yeah. And you notice—I mean, I must have realized on a very fundamental level that sound is powerful. And I lived in a house where more than one language was spoken. I learned to speak Italian first. And so I went off to college and I majored in comparative literature, because I knew some languages and I liked to read. And then I took a biology class and thought, "Oh, this is great. I love this stuff." And I also discovered a book called "The Biological Basis of Language" by Lenneberg and I thought, "Oh. This is a thing? This is possible? This sounds like something I'd like to learn more about." So I eventually got a Ph.D. in Neuroscience studying sound processing in the brain because I wanted to understand from a biological perspective, what is happening when we learn through sound, and initially much of the work was language-based, but soon, I realized that music is probably one of the best models we have for auditory learning. So we embarked on many studies looking at the effect of musical experience on the nervous system.

Jo Reed: Do you play?

Nina Kraus: I do.

Jo Reed: What do you play?

Nina Kraus: Oh, yeah.

Jo Reed: Piano?

Nina Kraus: I play some piano. I play some electric guitar. I play drums. I play harmonica. I like to sing harmony. None of these especially well, <laughs> but with great joy.


Jo Reed: The lab you direct, Brainvolts has such a robust website.

Nina Kraus: Thank you.

Jo Reed: Where people can actually go and discover as much as they want to discover.

Nina Kraus: Yes. Please, check out Brainvolts. So we update our website once, twice a day. There is so much that we're learning and we want to share it with you. It's www.brainvolts.northwestern.edu. And, you know, also if you'd like to follow us on Twitter and Facebook and we've just gotten an Instagram presence, so you can follow us @BrainvoltsNU on Instagram. You know, we love what we do at Brainvolts and we are excited to let other people know what our little discoveries are.

Jo Reed: And you're very good at communicating what they are, which is a pleasure on my end, so thank you.

Nina Kraus: You're sweet.

Jo Reed: Aw, thank you so much, Nina. I appreciate it.

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Jo Reed: That was Dr. Nina Kraus. She is professor of neurobiology at Northwestern University, where she directs the Auditory Neuroscience Laboratory, also known as Brain Volts.

You've been listening to Art Works, produced at the National Endowment for the Arts. You can subscribe to Art Works wherever you get your podcasts, so please do. And leave us a rating on Apple because it helps people to find us. For the National Endowment for the Arts, I'm Josephine Reed. Thanks for listening.

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Dr. Nina Kraus is a professor of neurobiology at Northwestern University where she directs the Auditory Neuroscience Laboratory, also known as Brainvolts. She has made the study of how we biologically process sound her life’s work. She and the Brainvolts’ team have conducted long-term, multi-year studies looking at the brainwaves of children and found that making music—whether with instrument or voice—actually makes biological changes to the way the brain processes sound which, in turn, strengthens the ability of the brain to better apprehend the depth and breadth of language and speech. Simply put, creating music builds our capacity to turn sound into meaning. Nina is passionate about sound—she remembers as a child sitting under her mother’s piano as she played. She brings that same sense of wonder and excitement to her rigorous biological research, and you’ll hear it throughout the podcast…which is a perfect way to explore the way we process sound.