basilar membrane

***From Gary Morrison***

>That's the ol' Helmholzian "place" theory. There have been more
>recent studies that suggest that lower frequencies are perceived very
>differently from higher ones.

Are you holding back on me?

>I certainly don't claim to be an expert on the topic though. Brian
>McLaren has surveyed a LOT of recent literature on the topic.

Did you get an idea of what conclusions he reached?


***Jesse Gay wrote***

>The basilar membrane is shaped like an elongated triangle.
>Different areas resonate at different frequencies, just as piano strings
>of different lengths resonate at different frequencies. So, when a sound
>wave travels down the basilar membrane, the membrane gets most excited @
>spots which resonate @ the frequency of the sound wave, or any of its
>partials.

So it's the width at various points? How do you respond to the assertion
made by Ewan Macpherson that it's the stiffness at various points?

>This explanation is the basis for the place theory of pitch perception,
>which, as you probably know, is not the whole story.

Actually, I've heard this before, but I've never heard what the whole story
actually is.


***From Ewan A. Macpherson***

>You're right, a point on the BM can't respond to only a single
>frequency. Instead each point acts like a bandpass filter.
>Excitation causes a travelling wave to move down the BM, and
>different frequency components of the wave peak at different places
>as it progresses. The portion of the BM nearest the middle ear is
>stiffest and responds best to high frequencies, and the membrane
>becomes increasingly floppy along its length, lowering the "best
>frequency" of the bandpass filters.

So it's the stiffness at various points? How do you react to the statement
made by Jesse Gay that it's the width at various point?

And what does this have to say about Helmholtzian place theory, and its
explaination of the critical band phenomenon?

Carl