A Defense of 'Noise'

Electrical engineer and writer Bart Kosko says not all noise is bad, and some could even help make you smarter. Kosko, author the book Noise, talks about how it can help with tasks such as signal processing.

Copyright © 2006 NPR. For personal, noncommercial use only. See Terms of Use. For other uses, prior permission required.

IRA FLATOW, host:

Up next this hour, something all of us are intimately familiar with. And that is noise. Researchers say noise, as you know, can cause stress, irritation and even shorten your lifespan, and if you feel like the world is getting louder all the time, you're right. From the train ride to the multiplex, the world's volume has been turned up and all of us are paying the price.

But why do some people appear to thrive in noisy spaces. I mean, I know some kids who can't do their homework without the TV or the iPod blaring in their ears. So just what is it? What defines noise? Is it just an unwanted sound or does it have to be a certain volume? Why is one person's really, really cool ringtone another person's headache?

My next guest has taken his thoughts about something many of us can do without and turned them into a book. Bart Kosko is a professor in the Department of Electrical Engineering at the Signal and Image Processing Institute at the University of Southern California. He's author of many books, Fuzzy Thinking and Nanotime. His new book is called, appropriately, Noise. He joins us from the studios of KUSC in Los Angeles. Welcome to the program.

Professor BART KOSKO (University of Southern California): Hi.

FLATOW: Hi there. Can you define noise for us?

Professor KOSKO: Sure. Noise, as you hinted at, is a signal you don't like. And what a signal is is something that conveys energy or information. So what noise really is, Ira, is unwanted energy. Any kind of interfering sound, or it could be visual noise, as in a TV or a computer screen.

FLATOW: Let me just correct myself. You're at KPCC, not KUSC.

Professor KOSKO: Yes I am.

FLATOW: I want to give full credit to KPCC in Pasadena there. So what do we know about the health effects of noise?

Professor KOSKO: Most are bad. There are a few good, but most are bad. As you said, noise increases stress levels and stress in turn increases a variety of maladies from increase of the probability of high blood pressure and heart attack and stroke and those kinds of things.

But most importantly, Ira, is noise induced hearing loss. That's the big problem from noise. It's always been a problem, but with the increase in more powerful, less expensive digital gadgets, noise induced hearing loss has increased, especially with young people.

A study in 1998 found in JAMA - the Journal of American Medical Association -that about 10 percent or so of teenagers had hearing loss comparable to old folks. And apparently it's much higher now, and it's only going to get higher with cheaper phones, again, that you can speak into at anyplace and headsets that you can blast that noise directly into your ear canal.

FLATOW: And, you know, you wonder about it because you could be sitting next to somebody with a pair of headsets on and you hear it almost as loud as they hear it.

Professor KOSKO: Exactly.

FLATOW: At least it's almost perceptible that way. And that's dangerous. What happens in your ear to lose your hearing?

Professor KOSKO: You lose the little hairs deep inside the inner ear, or cochlea, that detect frequencies. And you could think of them as a comb, although it's sort of rolled up. And each little tooth on the comb detects a specific frequency. Once lost, it's gone forever.

And so if you get a bump in the head or through simple aging processes, you'll lose a few. But through noise energy shot into the ear canal, especially above about 85 or 90 decibels - for example the level of a lawnmower - if you do that, you'll bend and break several. And you won't be able to detect those frequencies, or in some cases, Ira, you will always detect those because you bend the little hairs, the tooth of the comb, and you get tinnitus. This constant ringing of the ear, and there's really no cure for that.

FLATOW: Talking with Bart Kosko, author of a new book, Noise. He is talking about what makes noise. Our number, 1-800-989-8255.

I mentioned our world is getting noisier. Is it measurable to a scientist to actually measure how much noisier our world is today?

Professor KOSKO: Oh, it sure is. And a citizen can purchase an inexpensive noise meter for $50 to $100. There's been a lot of efforts to measure cities, for example in Europe, unlike in this country. All the major cities in the European Union have published a noise map. In fact, you can go online and look, for example, at London. Look at its sonic level. It looks like a contour map, different colors indicating how loud it is on average.

We don't have that here. And as a noise pollution, an anti-noise pollution advocate, I encourage all listeners to approach their local city council and simply ask them when do we get our own noise map. We can also measure things in our - well, it's important because, first it's going to affect your decision about where you're want to live. It's going to affect, more importantly maybe, the decision of builders and remodelers about the steps they can take. And they can take steps to reduce the increasing noise pollution.

Another case where there's lots of noise pollution we could measure is in the ocean. And the oceans apparently are about 10 times noisier than they were 50 years ago. And at any given time, there's a million plus boats afloat with depth finders. And the Navy has a variety of sonar. Some of them, for example, low-frequency sonars blast much more loudly than the takeoff of, say, the space shuttle. About 230 decibels. That's tended to -

FLATOW: No kidding.

Professor KOSKO: - apparently kill certain kinds of small creatures. Small beaked whales. In other words, after certain naval exercises, for example, in the Bahamas, four hours later they find several small beaked whales washed up on the shore dead, bleeding from their eyes and in effect from the ears.

And just in general, for example, humpback whales, they have to sing longer to maintain the same signal to noise ratio. Now sea creatures, Ira, you know, adapt in a very different way than land creatures. Water conveys sound more efficiently.

And so when you start noising that up, as we have unintentionally in a variety of ways, you interfere with something natural selection has taken many million years to tune. These signal processes. There was an experiment I talked about in the book Noise, controlled experiment with biologist worked with the Navy. When they turned on that Naval sonar, the whale songs increased substantially. When they turned it off they went back to their normal length.

FLATOW: Talking with Bart Kosko, author of Noise on TALK OF THE NATION: SCIENCE FRIDAY on NPR News. I'm Ira Flatow.

One interesting part about your book is it's almost like a ying and a yang aspect to it. One half of the book you talk about the threats from noise, and then in the other half you tell us how beneficial noises can be to us.

Professor KOSKO: Exactly. I would call it a fuzzy view. Noise is bad and noise is good simultaneously. And that's something, Ira, for me that occurred in my own research. For years as someone working with signals, initially in neural systems and brain systems and then in others in engineering, we try to conquer noise. We often call it the war on noise, and we have a variety of schemes for doing that.

The broadcast system we're using now probably uses a couple hundred of these different schemes in various ways as we go to from analog to digital signals and back and forth. And it was a great surprise when a lot of us found - in my case in the '90s, others in the '80s - that sometimes noise actually helped a system.

In particular, neural type systems or systems that trying to learn patterns and recognize patterns after they have learned them. We thought it was anomalous at first, but it turned out to be much like the phenomena of chaos. It sometimes related to it that it was really the rule and not the exception.

That, in general, for non-linear systems, complex systems, often a small amount of noise can help. Too much noise hurts.

FLATOW: Yeah. You have an illustration in the book of putting noise into a picture that's been washed out purposely. Is it random noise makes us actually perceive the picture better?

Professor KOSKO: It does indeed. We're not sure whether that's just in the page or in the brain or some combination of both. But if you take almost any image and, as you say, wash it out and add to it random pixel noise, at first it will get sharper. You'll see more edges and contours. Add still more noise, it'll get still sharper. But if you keep doing it, you'll destroy the image, you'll wash it away.

And that reflects, again, what we call an inverted U-curve where a little bit of noise, in some cases, a lot of noise, is a good thing. But if too much of it then you get back the classical world, which we viewed all noise is bad. What we sometimes call the Shannon world. The world of classical information theory and really the world of engineering post-World War II.

FLATOW: Do you think we have skewed the bad side too much?

Professor KOSKO: I think we have at that level. Because certainly one of the areas of research people like me work on - nanotechnology and quantum communication systems - are the benefits of noise. And partly because when you're at that tiny level, the universe is inherently noisy, very noisy.

It starts even with molecules and the Brownian motion of air molecules. But the further down you go in scale, the more random the nature of things. And so you, in effect, you have to cut a deal with the devil here.

But because, Ira, because that noise is fundamentally a form of free energy, you can exploit it, as nature appears to have done in many cases.

FLATOW: All right. We're going to take a short break and come back and talk more with Professor Kosko. Bart Kosko, author of the new book, Noise. And we'll take your calls. Our number, 1-800-989-8255. Stay with us. We'll be right back after the short break.

(Soundbite of music)

FLATOW: You're listening to TALK OF THE NATION: SCIENCE FRIDAY. I'm Ira Flatow. We're talking this hour about noise with Bart Kosko, professor in the Department of Electrical Engineering at USC and author of the book Noise. 1-800-989-8255.

We were talking about some of the benefits of noise, Dr. Kosko, and I needed to ask you - one of my daughters really seems to be able to work better on her homework whenever she's in a very noisy situation. Why is that?

Professor KOSKO: You know, that's a great question. It touches on a lot of research. But because noise is a form unwanted energy and therefore energy, it does tend to energize certain kind of systems. Well, what kind?

Especially the on-off kinds that our brains are made of. The neurons, the switches. And in fact, the main established benefits of noise in the animal kingdom and devices and mathematics have almost always concerned threshold-type devices. And, again, since your brain consists of about 100 billion of those, it's a natural conjecture that we get energized by noise.

For example, even the neurons talking to one another create noise for the other neurons. The neurons seem to have adapted to that. But I have had many experience with that myself. And I encourage people, Ira, to strengthen their brain this way by trying to read a book in a more crowded environment. Not to associate reading and thinking just with hothouse quiet activities.

If I could tell a story. I recently took the California bar exam to become a licensed lawyer in California as sort of a pastime or hobby. And it was a three-day exam and two of the days, the first and third days, were keyboard exams. The middle day was multiple choice.

And on those keyboard days, I had brought earplugs as had many of the other hundreds of candidates. And didn't need them. Because once the wild tapping at the keyboard started, it produced a wonderful background sea of noise that suppressed other noises. But more than that, it created that effect we're talking about. It energized my thoughts, and I was very short on sleep as I think other people were.

In contrast, on the multiple choice day, you could hear a pin drop and it was dull. I found myself wanting to fall asleep. I had missed that energy from the crowd. That kind of energetic background white noise, which studies show and the images we talked about before show visually, actually improve how non-linear systems work.

FLATOW: That would be interesting - to make that translation you say the studies show visually. Are there studies that show that in a noisy background you do work better or things do work out better for you?

Professor KOSKO: There have been a few. There'd been others that shown that interference can harm things. For example, you wouldn't at first order want to turn up the volume in the midst of a surgery and those kind of interferences. No one has, to my knowledge, looked just for a noise benefit there. That is called a stochastic resonance effect, by the way. Other instances they have, but it remains largely unproven at this point.

FLATOW: There's some research for anybody wanting to do that next paper. You seem to say in the visual side, there is that threshold, there's a limit, in other words, where they go too far. You muddy the picture instead of clear it up. I imagine the same thing in the auditory world is happening also.

Professor KOSKO: That's right. And in the book I talk about a formal result that I and some others arrived at called Forbidden Interval Theorems. Now that's a big name, but what it means is mathematically, as long as the average level of the noise doesn't fall within a certain boundary, as long as it's less than that or larger than that, you'll always have some kind of noise benefit.

And that's a guide we can use to see, first of all, whether a system we're dealing with, a visual system, an auditory system, can potentially benefit from noise and whether we're in the forbidden interval or not. And then once we decide that we are not in there, where noise will be a benefit, we have a variety of techniques that we can use to find the optimal level of noise to add to the system.

FLATOW: Gary in St. Louis. Welcome to SCIENCE FRIDAY.

GARY (Caller): Yes. I have, when I fly I have a pair of noise canceling headphones. And they work well in just making it easier to pick up the sounds I want to hear in the headphone. But I realize they work by just basically making additional noise but in the outside frequencies. Are there any detriments to that? Whether, in other words, if I were using them alot, am I giving myself a false sense of security? And I realize possibly it's not helping hearing loss but I'm talking about other physiological detriments to loud noises.

Professor KOSKO: Interesting question. You're right that the way it works in principle is to build a model of the noise and take its reverse, its mirror image, and add it to it and hence to cancel it, and further it has to track the noise source, so it has to be adaptive, and by the way it often uses something like a neural network, the very system we use to find the optimal level of noise to add to a system we add here to cancel it.

If you try to cancel a very loud noise, you'll tend to hear a background hum. And I guess in principle if that were loud enough, it could interfere with your hearing and other processes, but I haven't heard of any medical effects associated with it.

FLATOW: Thank you, Gary.

GARY: Thank you.

FLATOW: You know, there have been - on the Internet now there are these places that will sell you a ringtone for your phone that is at such a high frequency that only people under 30 can hear it. You know what I'm talking about.

Professor KOSKO: Yes.

FLATOW: Because we lose our hearing, our high frequencies, as we get older. And there are now even devices I've been reading about that people will put up outside a restaurant or in a public place to scare teenagers away by transmitting this high frequency, but older folks don't hear it.

Can you be damaged by a high frequency that you can hear that's very loud?

Professor KOSKO: Sure you can. And as you point out, as you get older - we talked about the comb that represents the frequencies - those upper-right portion of that comb, those hairs - a code for - high frequencies tend to go first, and that's often - what's often said, for example, why you can detect at a distance or get more sonority out of a man's voice than a woman's voice, because a woman's voice tends to have more of a higher frequency component.

FLATOW: So if you're subjected to a very high frequency, even though you can't hear it you could still be damaging your ear?

Professor KOSKO: Yes you could. At some point, though, we simply don't have frequency detectors at that level. But in effect if you blew a dog whistle at that level, you could damage those hairs, those cilia hairs.

FLATOW: Let's go to Bonnie in Sheldon, New York. Hi, Bonnie.

BONNIE (Caller): Hi. I'll take this answer off the air because I'm on my way to work, but I wondered if the doctor had any opinion on the noise that the wind turbines cause. There's a lot of controversy about that, testimonials from a lot of people, and there are some doctors who have said that it causes headaches, dizziness, upset stomach, it can damage your ears. I am wondering if he has any information and if he has a Web site. Thank you.

FLATOW: Thank you, Bonnie.

Professor KOSKO: I'll take the last one first. Yes I do have a Web site. If you just type my name, K-O-S-K-O, it will come at USC, and you can, for example, look at some of these noise papers and see the images where we add noise and improve the system or the visual image.

In the case of wind turbines, in general when you create power or transduce power, you do make a lot of noise. It does tend to be dangerous. It's not something you want to close to. Noise falls off with the inverse square of the distance, sound does, so to be a little bit close to a noise source makes a very big difference. I think most of those systems are designed with the idea that people won't be working around them unless they're OSHA protected, wearing appropriate hearing gear and other types of gear.

FLATOW: 1-800-989-8255 is our number. Let's see if Jeff in Portland is there. Hi, Jeff, welcome to SCIENCE FRIDAY.

JEFF (Caller): Hey, thanks for taking my call. Hey, I've noticed lately that a lot of my friends, including myself, have a hard time falling asleep unless they have like a fan going or some white noise of some sort, and I just wondered if you had any comments about that.

Professor KOSKO: I'm the same way, Jeff. I use a fan to create a white noise effect, in particular to mask background noise, especially if you sleep late in the morning and you have a lot of car noises. For example, there are something like 90 million leaf blowers in this country and the number is growing. And impulse noises of various types can take over, but a fan tends to do that.

It also, the white noise effect, if it's not too energetic, it can sound like a fountain, a waterfall. It does tend to soothe one. It energizes somewhat, but at the same time if it's not too powerful, it helps one sleep.

JEFF: Is there any link to, like, just the randomness of that, or?

Professor KOSKO: I'm not real sure why that happens. I do cite one study in the book Noise. If you have too much white noise at too high of energy level, it can damage the brains of baby rats, but that's the only negative I know of it. But we're not quite sure why that works. I've seen in some cases energetic white noise, the background hubbub of several conversations in a restaurant, will energize you and help keep you alert. In this case, a little bit tends to soothe you and help you sleep. It may just be the effect of masking other noises in the background.

FLATOW: Thanks, Jeff. Our number, 1-800-989-8255.

You talk about white noise, and we've heard that term for years. Are there other colors of noise that noise engineers talk about?

Professor KOSKO: All kinds of colors, Ira. There are pink noises and brown noises and black noises. That refers to the frequency spectrum. If you could wear special glasses like you see in some of the Star Trek sci-fi movies so that you could see the entire electromagnetic spectrum or a good chunk of it, and when you're listening to a sound, if you could see its frequency as engineers see through a prism they call the 4A Transform, then white noise would be the ideal case where the frequency is very flat and very long.

Now that can't really happen, because it would have to be so long and so flat that there would be infinite energy, but you can get a good approximation. If it's, instead of being flat, if it tapers a bit, it tends to be pink noise, and that sounds softer, and in fact the human ear will hear that pink noise as white noise. But any noise that isn't white, we call colored, and if it has got a lot of bumps in it in the spectrum, it's called brown noise. Now there are many cases where we use brown noise models to model phenomena. For example, the distribution of temperatures in a city seems to fit a model of brown noise.

And if the spectrum is really clumpy and jagged, we call it black noise. Now there are mathematical definitions of these, and they are not precise, they are fuzzy boundaries here, but we transition from an artificial ideal world of white noise, of a flat spectrum. As that spectrum becomes degraded, it gets more and more colorful, all the way down to black.

FLATOW: Let's go to Vin in Essex, Massachusetts. Hi, Vin.

VIN (Caller): Hi, good afternoon.

FLATOW: Hi there.

VIN: Thanks for taking my call. My question is regarding the amount of digital noise that everybody has as far as music goes. I'm an old guy that, you know, was brought up on albums and so forth, and I really don't like to listen to music these days on headphones at all, and I'm wondering, you know, with the amount of compression that all of these MP3s are using, whether that might inherently add to the, I guess, to sort of the dissonance of noise.

Professor KOSKO: I don't think the compression does, that's a different effect, but again if you're wearing a headset or ear pod devices, ear nubs, you're shooting noise, sound energy directly into the ear canal. It's very dangerous to do. If you do it at a loud volume, you're engaging in a high risk activity. You definitely should have your hearing checked at least once a year.

Young people tend to be doing this more frequently than older, but all people do. And as we mentioned before, those who listen on headsets, one good thing about that is that you're not imposing noise costs on third parties, on others. The downside is you're hurting your hearing. By the time you realize you've hurt your hearing, it's too late to correct it. There's no known cure for that. And further, if you listen to headsets in loud environments, as so many people do, you tend to up the volume and hurt the hearing all the more.

FLATOW: Thanks for calling, Vin. Our number, 1-800-989-8255. We're talking with Bart Kosko, author of the new book called Noise on TALK OF THE NATION Science Friday from NPR News.

The fact that we are all in the iPod generation and listening through headsets and shooting this noise directly into our ears means that somewhere down the road, we're all going to be more deaf than this generation or have hearing problems worse.

Professor KOSKO: It sure does. And it looks that way that - again, it began with, say, rock musicians, and there are movements afoot from rock musicians themselves to help us become aware of hearing damage. But young people who listen to music at rock concert levels, which is about 130 decibels, almost surely have some kind of damage, and the younger you are when you damage your hearing, Ira, the worse it's going to be over time because you may continue to lose things through the aging process, but in addition to that you're probably going to be cranking up the volume just to compensate for the hearing loss in your youth, and you'll just speed up the process.

FLATOW: Is there, and this may be a little bit far a field of your range, but talking about noise and isolation - are we in a generation where people who are in this generation are losing their interaction with the rest of the world because they're so clammed up inside these, you know, these ear pods?

Professor KOSKO: I think that's a part of it. One effect I've noticed, if you're standing in a checkout line, there are certain norms and customs you follow. Most people try not to look at the driver's license of the person writing the check, for example, and we all just bide our time, but when that cell phone rings and someone pulls it out, they are no longer in that little society. They're suddenly talking to the person on the other end of the cell phone, often quite loudly, and once they have crossed that line, you know, they don't seem to go back, and that sends a signal to everyone else that that's the rule of fair play now and it tends to only go up.

I've noticed also when the airplane lands and people stand up to get their language is when the cell phones come out, and it seems as if more and more people treat others like rental cars here, that we talk directly and loudly about our personal events, you know, really not thinking about the noise effects we're imposing on others.

It is getting worse, by the way, and I think at least in places like California, if that continues, it'll go the way of secondhand smoke and may very well lead to cell phone limits.

FLATOW: You think we'll have laws against noise pollution?

Professor KOSKO: We do have laws against it right now, but against cell phone usage in public places, I think that's inevitable. If people simple won't tone it down, that'll happen, and again the unintended consequences as more people use these phones, it encourages others to do it both because you need to do that to maintain the signal to noise ratio, you need to speak more loudly, in effect, when everyone else is being loud, and two, you see everyone else doing it and so why not you?

FLATOW: Is there a cutting edge in noise research? Where would it be?

Professor KOSKO: I think it is - there are edges in noise research. One would be in the case of canceling noise, and that's always going to be ongoing. But I'll say again if we take it to the very small level, to the quantum level, to the nanotechnology level, we have to learn to adapt to a very noisy environment.

I did an experiment with some students. We took a carbon nano-tube, a very tiny piece of carbon, it looks like rolled-up chicken wire, the carbon molecule, and I used it as an antenna to recognize signals, and we showed that if you add very faint electrical noise, the kind of stuff that's in the background anyway at that level, you can improve how it receives signals.

Now one thing you could do, Ira - no one's done this - but you could take those tiny carbon nano-tubes and use those to replace those missing hairs in your inner ear, in theory greatly improve it, to increase your frequency spectrum and make it more redundant. And I know there are a lot of research groups looking at that kind of thing.

Likewise at the very forefront of quantum computing. We're trying to do is design new kinds of computer that have to work in the presence of noise. I and my students and others have shown that by adding noise to the quantum channel, you can actually improve the overall amount of information that you can send through it, within limits, and we hope to test that someday.

FLATOW: Well, we all have our assignments for the weekend, those nano-tubes.

Professor KOSKO: We do indeed.

FLATOW: Thank you very much, Dr. Kosko.

Professor KOSKO: Thank you.

FLATOW: Bart Kosko is professor in the department of electrical engineering at the Signal and Image Processing Institute at USC. His book is called Noise, very interesting.

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