Radiolab

Navigate
Return Home

Ears don't lie

Friday, December 28, 2012 - 05:00 PM

We humans are visual creatures. But maybe we should reconsider.

"Eyes lie," says auditory neuroscientist Seth Horowitz. "But the ears don't."

Horowitz's field of study -- how sound rattles around in our brain -- is fascinating. A short run-in with him before Christmas has me knee-deep in auditory explorations: repetitive tones, videos of kids in music class, and a raft of Google searches.

According to Horowitz, our auditory-bending brain may be one of the best things we have going for us. I mean, he's pretty biased (Horowitz is the author of the new book, “The Universal Sense: How Hearing Shapes the Mind") -- but seeing him speak at New York City's The Museum of Modern Art, I was pretty blown away by what I was hearing about hearing. And I thought, hey, the holidays are here, you've probably either run out of one-liners to see you through another get-together and could use a little cocktail party science top-up, or you're itching for some fake excuse to sneak away from all the family time for a minute (e.g., "Hey, ma, I'll be right there, I just need to check in with, um… work?!")

So, I invite you to plumb… not the depths of our sense of hearing... because, let's face it -- I'm not going that deep. But here are some tidbits to see you through until we have a for-real, actual sit-down with Horowitz (and/or, I finish his book). Which is good, as it gives y'all time to send in questions about sound and the brain. (And to listen to our shows on Pop Music and Musical Language.)

Speed of sound:

Hearing is our fastest sense. (Who knew?!) Horowitz says that it takes our brain at least one-quarter of a second to process visual recognition. But sound? You can recognize a sound in 0.05 seconds. And our brain is so adept at hearing the differences between sounds, we can sense changes of sound that occur in "less than a millionth of a second," according to Horowitz's book. Why this need for auditory speed? It's our evolutionarily-shaped emergency response system. It let our ancestors hear a twig snap in the woods at night, when all was supposed to be quiet and they couldn't see. Yet, for most of us, we're wired to tune out non-essential sound, so the world doesn't feel like a sensory overload.

Honest ears:

Remember optical illusions, those eyeball oddities that make it appear like circles are moving and vases are faces? It turns out, there are no auditory illusions in nature (that's how honest our ears are, you can't trick 'em), says Horowitz. Instead, any audio paradoxes you hear are created by technology, and there are only 10 by his counting. One he played for us is known as "the shepard tones." Have a listen, and then we'll explain it:

                         

In this series, created by electronic composer Jean-Claude Risset, the tones seem to be continually ascending in pitch when in fact… it's the same series of tones, being played in a loop; and that loop always ends up where it started. It's like an auditory version of the famous Escher stairs painting. Now, I don't yet know how this works (not sure what it does to mess with the brain, but if you do, let us know); so for now let's just settle into the fact that it's crazy.

When diving into the internet world of audio paradoxes, I came across one that Horowitz didn't play for the crowd. It's less of a paradox, and more of a technique. A mind-blowing technique. When the video below started, I flipped over my right shoulder to see if someone had opened the door to come into the room (I wasn't in a room, there was no door). Have a listen, and make sure you're wearing headphones (there are actually no visuals, so close your eyes to make it even better):

                         

As they said in the audio, they created this sound by sticking microphones in a dummy's head. Making it sound like it was in your head. Weird.

Sleepy sounding:

Did you know that when you are in a bar, all the noise -- the clash of glasses, yell of a bartender, and couple fighting in the corner; the jokes of friends, slam of the door, and music jamming from the jukebox -- activates our body's flight or fight system? In response to that, the body wants to do something, anything, to manage the adrenaline that's pumping through its veins. In this case, that means spend money. Eat more. Get another round. Well, Horowitz and his team are interested in this and other ways our body reacts to sound. Specifically, they are interested in understanding how sounds make us feel, then isolating sounds that make us feel a certain way and putting them to use.

So, among others, his team is looking into the sounds that: help us concentrate, make us feel nauseous, and put us to sleep. His thought is not to use them in a Big Brother sort of way (imagine a store with the ability to play tracks that make us buy, buy, buy!) but to, say, help a student perform better on a test. Or help a journalist concentrate in the midst of a bustling news room. In fact, he's already released a sleep CD, wherein low-frequency recordings are overlaid onto classical music. And these low-frequency sounds are often inaudible -- it's not about us hearing them, it's about our brain doing so; it's about how they turn on the brain. For example, one of the low sounds on the CD activates the same area of the brain that is pinged when riding in the back of the car on a long trip, when you just can't help but fall asleep. (Turns out, writes Horowitz, falling asleep in cars, even when it's important for you to stay awake, is actually another form of motion sickness, called Sopite syndrome.)

Sound that puts you to sleep, sounds that go bump in the night, and sounds that don't lie -- you see why I can't stop thinking about my ears? But if it's not enough, I'll leave you with this: you can thank Horowitz the next time the T-Mobile ringtone interrupts your movie date -- he and his team created this addictive jingle using a computer algorithm based on four notes, inspired by the grey squares and pink T of the T-Mobile logo.

 

 

Tags:

More in:

Comments [14]

rhonda strickland

Patrick: the ear doesn't lie when it is a healthy ear functioning normally. Tinnitus is an example of a malfunction, just as hearing loss, stuffed up ears, etc. would be.

Oct. 17 2013 03:07 PM
Sara from Portland

Patrick, to answer your question- tinnitus is not the ear lying, b/c the brain actually produces tinnitus...not the ear. This is top-down process (brain to ear). It is very common for people with hearing loss to experience constant ringing (aka tinnitus). The brain wants to receive sound, and when it does not (in the case of hearing loss, where sound used to be present but now is not), essentially it just makes its own sound.

Feb. 01 2013 03:55 PM
karen judkis

just heard your piece on physician end-of-life- preferences. good stuff. maybe you could do a show on hospice care and the importance of having an advance directive(living will).

Jan. 29 2013 11:05 AM
Jim from Colorado

Fascinating observations on sound. I think part of the reason the endless loop of seemingly higher tones works is the way the tone slides upward into the note. It gives a sensation of higher pitch each time you hear it, even though it is actually starting at the same place and ending in the same tone.

I really enjoy my 7.1 home theater - it really helps immerse the viewer in the movie. One of the most distressing movie special effects is in Toy Story where Woody is rotating around on the ceiling fan. He is always on the screen, ever quite going out of view behind the audience, yet the sound goes completely behind. Very distracting and distressing because he is still on the screen in front of us, but the sound comes from behind. Really messes with the mind!

I found this part of the article interesting: "Why this need for auditory speed? It's our evolutionarily-shaped emergency response system. It let our ancestors hear a twig snap in the woods at night, when all was supposed to be quiet and they couldn't see." Kind of amusing to me that those who believe in evolution are constantly finding ways to confirm what they already believe. But, as an earlier comment points out, a snapping twig in the dark leaves much to the imagination. Wouldn't it be better to have eyesight that worked in the dark? Why didn't we evolve with bat-like radar? Perhaps because we didn't evolve at all.

There are many flaws with evolutionary theory. It might be more plausible if there were an explanation for life and how life started. And for the Cambrian explosion. And the lack of evidence in the fossil record for the transition from sea to land, invertebrate to vertebrae, etc, etc.

Even more amusing was the author's differentiation between the brain and the person: "And these low-frequency sounds are often inaudible -- it's not about us hearing them, it's about our brain doing so; it's about how they turn on the brain." If the brain isn't "us", then who is "us" ? Why, we are the soul that resides in the body! The author tacitly acknowledges that we are not our body and our body is not us.

Eyesight and hearing are extremely complex systems that pretty much defy evolution. But I'm very happy to have both senses!

Jan. 11 2013 07:28 PM
even steve

Horowitz says that it takes our brain at least one-quarter of a second to process visual recognition.

This is just flat out wrong. A lot of visual recognition processes are mostly complete in 50 msec, same as sound.

Jan. 09 2013 11:19 AM
patrick wimsatt

If the ear doesn't lie, how do you explain tinnitus?

Jan. 09 2013 12:48 AM
rarcher from portland, or

more auditory illusions:

http://deutsch.ucsd.edu/psychology/pages.php?i=101

Jan. 08 2013 06:27 PM
jimbatcho

Neither sense "lies," they both interpret. But they interpret in different ways. Sight is an acquiring of of sense data; hearing is a response to sense data. Both are linked to survival. See the bunny, catch the bunny. Getting food. Hear the lion behind me, run from the lion. Not becoming food. The former is managing objects in physical space, understanding the objects, placing them in space, and then moving through space. The latter is receiving objects in a particular space and understanding their location.

The wacky thing with sound is it is so... nonliteral. It's an emotional response and a kind of instant puzzle. What is that?! If it is tied to a visible object, we can better understand its meaning. If it is not, we have to guess. Sound actually goes to two places in our brain: a logical center and an emotional center. But the emotional path is much faster, which is why a sudden loud noise behind us freaks us out.

This is also why "offscreen" or nonvisual sounds in horror movies work so well. We have to do the work to interpret what they mean. I also believe that this is why music works. Because we don't have a visual component, it resides purely in the emotional realm. It takes the necessary fearful/survival emotions of sound and organizes them into something beautiful. Beauty is simply organized fear.

Jan. 04 2013 09:19 PM
scott saults

The "Shepard tone" illusion is based on the work of Roger Shepard (who obviously should be credited above). See the wikipedia article: http://en.wikipedia.org/wiki/Shepard_tone
The illusion is based on our tendency to perceive pitch in relative terms based on frequency intervals within an octave. Two tones exactly an octave apart are perceived as similar, because they actually are the same 'note' in musical terms. See the article: ^ Roger N. Shepard (December 1964). "Circularity in Judgements of Relative Pitch". Journal of the Acoustical Society of America 36 (12): 2346–53.

Jan. 04 2013 01:49 PM
Chris

When I was 6 years young, a teacher asked everybody to write down the most important sense we have.
Everyone wrote 'eyesight', except me thought it was 'hearing'.
Every kid laughed with pity and the teacher wasn't too kind either.

Today I have been a musical instrument maker my entire adult life.
And I am still learning and experimenting with the endlessly fascinating world of sounds and music.

My latest gear is a guitar/studio sound effect using the Doppler effect in stereo.
Blending acoustical physics with musical sounds is very inspiring.

Jan. 02 2013 11:13 AM
J Noyes

Trained ears (musicians) can hear the loop being played right away.

Also, don't use tmobile, thank goodness. There are definitely not 4 different pitches being used.

Dec. 31 2012 11:40 AM
Molly from NYC

Jon from Seattle -- thanks for the great explanation!

Dec. 31 2012 09:35 AM
Steve Hay from Modesto

My hearing is much easier to fool than my vision as anyone who has heard a sound effects performer knows. For instance, voices are harder to pinpoint than a face which is so easily recognizable. It is my experience that our hearing matures later than vision. Not until we are in our early teens do we seek out jazz and intricate auditory experiences. Our eyes have 126 million direct receptors (cones and rods) but the cochlear receptors average 30,000 and all this sound must first travel through a single eardrum. Thus it must be sorted in a sequence and matched with memory (identified) using less “equipment” than vision. Nor is our processing center as large for our hearing sense compared to our visual (it gets a cortex all to itself). For an audio based media program you certainly give hearing a short shrift.

Dec. 30 2012 08:36 PM
Jon from Seattle

Although I haven't worked out the math, I believe the reason that the ascending music loop works, is because of the way that the overtones on each note overlap with each other. For example, when you play a C on a piano, the harmonic series generated is actually the fundamental (C) and the octave (C) and the 5th above the octave (G) and the next octave (C) and then 3rd above that (E) and then the 5th again (G) and then a note that is between the major and minor 7th, and then the octave again, and so on. That's a lot a C's starting to stack up. In the middle of the ascension, it's hard to tell when one of the C's in the top drops off the top and one get added to the bottom of the right had (because most of the overtones are the same). Where you do notice is on the very low end, when the base line drops back to the beginning. Our ears don't hear low frequencies as well, so you don't really notice until you're looking for it.

A similar "illusion" exists with you have an orchestra that is precisely in tune. If you have 1/3 plan a low C, 1/3 play a middle C and 1/3 play the G between the two C's, your ear will hear the E above middle C even though no one is playing it. It happens because the superposition of those harmonics make the E loud enough to stand out to the ear like it's a fundamental.

Dec. 28 2012 06:29 PM

Leave a Comment

Email addresses are required but never displayed.

Supported by

Feeds