What determines the frequency range we can hear?

Ron Blue rcb5 at msn.com
Mon Apr 2 03:40:50 EST 2001


""rico r"" <turboflier at hotmail.com> wrote in message
news:F114cJMSF1FmOJ4IXol0001b2f0 at hotmail.com...
> How come bats can hear up to 130 kHz while we can hear up to 20 kHz?
> Obviously we dont NEED to hear a such a high frequency, but what determines
> the frequencies we can hear? Does it have anything to do with the size and
> structure of the cochlea (or the sensory hairs)? Also, do specific nerves
> respond for specific frequencies, or do the impulses just get faster? I
> would imagine that individual nerves fire for a specific frequency, and how
> fast they fire determines the volume of the sound.  I was just curious
> because i cant give myself any reasonable explanation, nor could i find one.
> Thanks!
>
> Rico Reyes
> High School Senior
> California

Currently there are difficulties explaining reasonably the ability to hear
sounds at very high frequencies, because the fastest nerve cell is about 1 kHz.
Sound is stored in short term register for about 3 seconds.
So it should be obvious that hearing is not due to individual nerve cells
creating a one to one correspondence between nerve impulses and a sound.

Parallel processing, harmonics of interaction, and timed summation due to
multiple locations of nerve cells then becomes a reasonable guess.  Another
possibility is the large number of opponent nerve cells coming from the brain
creating an type of holographic wavelet filter interacting with the stimulus
input.  If this approach interest you check out my web site at http://turn.to/ai
.

Ron Blue







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