Re: mechanical cochlear model (Linda Seltzer )


Subject: Re: mechanical cochlear model
From:    Linda Seltzer  <lseltzer@xxxxxxxx>
Date:    Tue, 22 Feb 2011 13:59:53 -0800
List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>

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@xxxxxxxx . >


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