Re: BM motion

[Matt Flax <flatmax@xxxxxxxx>]

Hi list and Richard,

Travelling waves have no mechanism for high side suppression... 
it is simply not possible.

Clearly in the literature [1] last paragraph for example ... here 
is an excerpt :
... neither models nor experiments have yet answered what
is perhaps the central question of mammalian cochlear
physiology, namely, the origin of the CF specificity of
two-tone suppression and other mechanical nonlinearities.

I have other references.

[1] 
@ARTICLE{Ruggero:1992,
  author = {Ruggero, M.A. and Robles, L. and Rich, N.C.},
  title = {Two-tone suppression in the basilar membrane of the cochlea: 
mechanical
	basis of auditory-nerve rate suppression},
  journal = {Journal of Neurophysiology},
  year = {1992},
  volume = {68},
  pages = {1087-1099},
  number = {4},
  month = {October}
}


On Tue, Nov 13, 2007 at 08:22:06PM -0800, Richard F. Lyon wrote:
> No matter how the nonlinearity affects the tone amplitudes, the sum of two 
> sinusoids of different frequencies is easily distinguishable from a larger 
> single sinusoid, through the temporal pattern, which will be appararent in 
> the auditory nerve firing-time patterns, even when both frequencies are 
> higher than can be coded by synchrony.
>
> As to the nonlinearity, it shows up clearly in the mechanics, when the OHCs 
> are functioning, and it's not hard to see how OHCs in one region can change 
> the response to other tones that travel through that region to be localized 
> further on; that is, how high-f can suppress low-f if not too much lower.  
> The other direction works slightly differently, but the key is that 
> different frequencies share the same traveling wave medium that amplifies 
> them, so you get suppression.  There may yet be mysteries in the 
> micromechanical details, but not in the overall functional effect.
>
> Matt, is the "'frequency specificity' mystery" something that you find in 
> the literature?  Or do you just mean you haven't found a clear enough 
> explanation?
>
> Dick

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