Re: mechanical cochlear model

[Linda Seltzer <lseltzer@xxxxxxxxxxxxxxxxxx>]

My vote is to keep the discussion on the list, and the postings do not
have to be short.  I believe that it is laudable when people want to
provide education to others and share the benefit of their expertise.
> Hello !
>
> I, too, would be glad if the cochlear-mechanics discussion on the Auditory
> List could continue. If possible, the postings should be kept short.
>
> Today I would like to continue my point-by-point comments
> on the posting of March 7 by Andrew Bell:
>
>>In addition to Martin's 2 pieces of evidence against the traveling wave
>>model, we can add:
>>[...]
>>2. The variation in stiffness is inadequate to tune the cochlea from 20
>> to
>>20000 Hz. Three decades of frequency calls for a million times variation
>> in
>>stiffness (more than between foam rubber and tungsten), and this is in
>>contrast to measurements of 2 or 3 orders at most. See Naidu & Mountain
>>1998, Hear Res 124, 124. Bekesy found the value to be about a
>> hundred-fold
>>(p. 476 of Exp in Hearing).
>
> The human BM resonance frequency, f_BMR = (1 / 2pi) * sqrt(S / M) at
> the base appears to be about 20 kHz. At the apex, however, that
> resonance frequency may well be considerably greater than 20 Hz.
>
> Both in post-mortem and healthy cochleae, the travelling wave does
> not reach the BM resonance place. At given frequency >1 kHz the
> passive (active) response peak is basal of the BM resonance place
> by about 1.0 (0.5) octave distance. In homo, that distance is ~5mm.
>
> Reinhart.
>
> Reinhart Frosch,
> Dr. phil. nat.,
> r. PSI and ETH Zurich,
> Sommerhaldenstr. 5B,
> CH-5200 Brugg.
> Phone: 0041 56 441 77 72.
> Mobile: 0041 79 754 30 32.
> E-mail: reinifrosch@xxxxxxxxxx .
>