In article , Nick Gorham
wrote:
Dave Plowman (News) wrote:
In article , Andy Evans
wrote:

How does the cochlea separate a complex sound into its different
frequency components?


It doesn't - it's part of a simple microphone. The brain does the
clever bits.


I woudn't argue that the brain does the clever bits, but the little I
have read about the subject shows that the operation of the cochlea is
nothing like any microphone I have seen, and is far from simple.

It is. :-) I've been looking into this in recent years, and the current
physiological understanding of the cochlea is mind-bogglingly complex. One
model is to regard it as a non-linear dispersive set of linked transmission
lines (with characteristics that vary along their lengths) upon which the
sensors are a series of non-linear *active* resonant detectors whose
effective gain and bandwidth vary with the signal levels they experience.

(This only covers the physical/mechanical side. After that comes the
nerves.. and I've also ignored the biochemistry of what 'pumps' the active
parts of the system. ;- )

I've now written a few articles on this for mags like "Hi Fi News", and
some of the material is now at

http://www.st-and.demon.co.uk/AudioM...ing/index.html

if anyone is interested.

Bear in mind that what I've written is very much a *simplified* version of
what the physiologists now use as a model, but even so it has some
surprising implications for audio/hifi... :-)

Slainte,

Jim

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