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Re: Laws of physics and old history; BM stiffness.


The following is a reaction to an earlier post of this thread:

As already posted some years ago, it appears possible to me that the stiffness S [Newtons per m^3] of the mammalian cochlear basilar membrane (BM) decreases by several orders of magnitude from base to apex. If the elements of the BM are treated as elastic beams, then the following formula for S is obtained:

S = n * Y * (delta-z)^3 / w^4,

where delta-z is the beam thickness, w is the beam length (equal to the BM width), and Y is Young's modulus of the beam material (elasticity modulus, Newtons per m^2); the integer n depends on the way in which the beams are fixed, at their ends, to the walls of the cochlear channel. If the beams are clamped, then n = 60, if not, then n = 10.

Fig. 11-73 of von Bekesy's book "Experiments in Hearing" (1960) yields a human BM stiffness decrease of only two orders of magnitude from base to apex. Has that experiment been re-done? 

Reinhart Frosch,
Dr. phil. nat.,
CH-5200 Brugg.
reinifrosch@xxxxxxxxxx .

----UrsprÃngliche Nachricht----
Von: rsran@xxxxxxxxxxx
Datum: 09.11.2011 20:17
An: <AUDITORY@xxxxxxxxxxxxxxx>
Betreff: Re: Laws of physics and old history (A new paradigm?(On pitch and periodicity (was &quot;correction to post&quot;)))