Re: mechanical cochlear model

[Jose Ignacio Alcantara <jia10@xxxxxxxxx>]

A heartfelt ditto to this!  Long may they live and prosper on this list.
Jose
  
On 22 Feb 2011, at 21:59, Linda Seltzer wrote:

> 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 .
>> 

Dr José Ignacio Alcántara

Department of Experimental Psychology
University of Cambridge
Downing Street
Cambridge, UK
CB2 3EB
Phone: 44 (0)1223 764412
Fax: 44 (0)1223 333564

Fellow of Fitzwilliam College
Cambridge, UK
CB3 0DG
Phone: 44 (0)1223 472126