Re: Laws of physics and old history...

[Andrew Bell <andrew.bell@xxxxxxxxxx>]

Dick Lyon wrote:

> It's not 
> that complicated, really. 

Well, if you're looking for a nice compact equation to describe the motion
of the basilar membrane as seen from a distance, it's OK, but if you imagine
you're a hair cell, it's not that simple at all.

First, sitting there on the BM, you have to decide whether the motion you
sense is meant for you, or meant to be passed on to your neighbours (the
feedforward idea of cochlear amplification that's favoured in TW theory at
the moment).

Second, you are meant to have a certain characteristic frequency, but the
peak of the TW keeps moving around, depending on intensity (Lighthill,
Patuzzi). The peak of the wave is reached _before_ the resonance frequency.
So how can the peak be accurately signalled? The brain must have a terrible
job putting all the information back together just to reconstruct a sound,
and we have not yet even mentioned distortion products.

Isn't it simpler to have a system with one place, one resonator, one
frequency?

Yes, a second-order resonator does have some limitations, but it's on the
right track. You might need to refine the response a little, but what's
physically unreasonable in having a bank of local resonators arrayed along
the partition whose frequencies are set by local parameters? It may not be
as neat for the mathematician, but the world is not made to make life easy
for them.


Andrew.