• Register
  • Help
Results 1 to 7 of 7

Topic: The inner ear emits sounds and harmonics according to a new study

  1. #1

    The inner ear emits sounds and harmonics according to a new study

    According to this article, medical researchers have found that the inner ear produces musical notes and harmonics in what they call "squirting waves." (No sample sets are currently available.) According to the article, the scientists suggest that these ear sounds challenge the theory that sound is made of waves. (As though resonance and waves were mutually exclusive notions, apparently...) I think the reporter slightly misunderstands the scientists--what they seem to be describing is the resonance of the cochle in fluid, and the harmonics it creates among other cochlea. The ear doesn't itself emit a note, except the harmonics, independantly of an outside sound. Not until they put those chips in our heads. (Another article describes the situation better: http://arc.cs.odu.edu:8080/dp9/getre...ton.ac.uk:1735 )

    At the end of the first article is a link to an mp3 of the sound of the inner ear:

    The link to the first article (so you'll know this is not a joke):


    The article:

    The inner ear functions like ‘an underwater piano’ – highly tuned despite being immersed in water – according to a new explanation of how we hear by two ANU researchers.

    Their paper, in the respected Journal of the Acoustical Society of America, provides a new understanding of how our delicate sense of hearing might work, explaining why most human ears continuously emit soft, pure tones that can be picked up with a microphone placed in the outer ear.

    The hypothesis was formulated by Mr Andrew Bell, a PhD student at the Research School of Biological Sciences and developed mathematically by Professor Neville Fletcher of the Research School of Physical Sciences and Engineering.

    “Like a piano, the cochlea is highly tuned, and yet, paradoxically, it is filled with watery fluid”, Mr Bell said. “Our paper explains how the ear can overcome this apparent contradiction by using a special wave known as a ‘squirting wave’, which so far has only been recorded by scientists working in ultrasonics.”

    Squirting waves occur when two closely-spaced flexible plates, surrounded by fluid, vibrate. Fluid jets are created as the plates alternately squeeze together and pull apart – much like clapping hands underwater – and the jets, interacting with the bending of the plates, give birth to squirting waves.

    The paper demonstrates how the unique properties of squirting waves allow the cochlea to respond sympathetically to the lowest audible frequency, such as the deepest drone of a pipe organ; to the highest, such as the tinkle of a triangle.

    “Resonance is what makes a wind chime work, and the cochlea seems to have thousands of such chimes,” says Mr Bell. “But because the cochlea is filled with liquid, it has to overcome what seems an insuperable obstacle – viscosity.

    “Lowering a ringing wind chime into water will silence it. Several decades ago a key auditory scientist, Thomas Gold, well described the cochlea’s problem: like a piano with the sustain pedal on, it needs to vibrate in sympathy with incoming sound, but given water’s viscosity, how do we get such an ‘underwater piano’ to work?”

    The cochlea does the trick by using special piston-like cells to create squirting waves between two thin membranes, according to Mr Bell. It makes the surfaces extra slippery by coating them with oil and then uses positive feedback to overcome the remaining viscosity. Working together, these techniques create a fully functioning ‘underwater piano’ that can respond to the slightest whisper.

    “Our paper might help provide a clearer picture of what is going on with tinnitus, a mysterious ringing in the ear which millions of people around the world experience,” Mr Bell said. “At the most fundamental level, it could provide a basis for reinstating the long-neglected resonance theory of hearing which has, for more than a century, taken a back seat to the currently-accepted travelling wave theory.”

    Hear a recording of tones emitted by the ear recorded by Andrew Bell (2.5MB)


  2. #2

    Re: The inner ear emits sounds and harmonics according to a new study

    very interesting

    thanx for the links

  3. #3
    Senior Member
    Join Date
    Oct 2004
    Los Angeles, CA

    Re: The inner ear emits sounds and harmonics according to a new study

    That's very interesting! I suppose it could be argued that since we are electrical creatures, there could be something like a "60Hz hum" going on in our brains/hearts/bodies.

    Also have you ever just been sitting around and suddenly heard a very high frequency in your ear? Apparently that's the sound of one of the cilia (hairs) in your inner ear "kicking the bucket".
    Some experts learn more and more about less and less, until at last they know everything there is about nothing at all.

  4. #4

    Re: The inner ear emits sounds and harmonics according to a new study

    Actually, current opinion is that the ear can create notes without an outside stimulus. Research into tinitus has shown that, for some subjects, the high ringing frequency can actually be detected by a microphone placed down the ear. Whereas it was previously believed that tinitus was entirely in the mind, it is now believed that some cilia are oscillating all by themselves.

    The theory is that we actually have motor control of the cilia, and can deliberately focus on specific frequency bands by causing groups of them to 'amplify' their oscillation. Tinitus is a case where the brain is sending rogue signals to groups of cilia, to amplify their oscillation, even when there is no external stimulus.

    Whether the explanation is right I don't know - my dissertation was somewhat tangiential to this - but the phenomenon of being able to actually record the ringing from a subject's ears is fairly old news. And proof that combination frequencies are actually created on the Basilar Membrane is even older.

  5. #5

    Re: The inner ear emits sounds and harmonics according to a new study

    Just another transducer, apparently...
    Houston Haynes - Titan Line Music

  6. #6

    Re: The inner ear emits sounds and harmonics according to a new study


    Hm...Is there a standard frequency the ear emits, or a range?

  7. #7

    Re: The inner ear emits sounds and harmonics according to a new study

    Not a clue. I went back to my notes to find out where I'd read it. The article I read was,

    'Zurek P.M. (1981): Spontaneous narrowband acoustic signals emitted by human ears, Journal Acoustic. Soc. Am. 67, 952-964.'

    I've also noted that he called the phenomenon 'spontaneous oto-acoustic emissions' and as much as I wrote in my last post. But that's it, so I'm afraid I don't know if there is a common frequency for the phenomenon or not.

Go Back to forum


Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts