Re: mechanical cochlear model

[Peter van Hengel <pwj.vanhengel@xxxxxxxxx>]

Dear Martin,

 

interesting results no doubt, but once again I must protest against the conclusions. As I have stated before it is not so easy to abolish or greatly reduce the traveling wave in the cochlea. Any motion of the fluid, in combination with the flexibility of the BM, will cause a traveling wave, even if you severely influence the boundary conditions.

Oversimplification of fluid mechanics in the cochlea has led to erroneous conclusions before...

Just a warning against drawing conclusions too rapidly.

Regards,

Peter

2010/6/2 Martin Braun <nombraun@xxxxxxxxx>

Dear List,

New data have appeared that are again consistent with each of the following two hypotheses:

A. Cochlear macromechanics has no role in hair cell excitation near threshold of hearing.
B. Cochlear macromechanics has an important role in hair cell protection at excessively high sound levels.

http://www.neuroscience-of-music.se/Sohmer2.htm

Enjoy,

Martin


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Martin Braun
Neuroscience of Music
S-671 95 Klässbol
Sweden
email: nombraun@xxxxxxxxx
web site: http://www.neuroscience-of-music.se/index.htm





----- Original Message ----- From: "Martin Braun" <nombraun@xxxxxxxxx>
To: <AUDITORY@xxxxxxxxxxxxxxx>
Sent: Saturday, March 06, 2010 10:29 PM
Subject: Re: mechanical cochlear model


While the cochlear traveling wave has appeared in numerous empirical reports
on real physical models and real biological animals, it's function in
hearing is not yet universally appreciated. Some people still think that it
provides the well known frequency selectivity that we observe in the
auditory nerve. This view, however, has been proved wrong by multiple direct
experimental evidence. Just consider two bodies of evidence:

1) Hearing sensitivity is not affected, when endolymphatic hydrops presses
the basilar membrane flat upon the bony cochlear wall of the scala timpani:

http://www.neuroscience-of-music.se/Nageris.htm

http://www.neuroscience-of-music.se/Xenellis.htm


2) It is a well established observation for more than 50 years that closure
of the round window does not affect hearing sensitivity. This means that a
pressure difference across the basilar membrane and a resulting traveling
wave cannot be a necessary condition of hair cell excitation. Recently,
Perez et al. (2009) reported that closure of the round window not only
leaves hearing sensitivity unchanged but increases cochlear vulnerability at
high sound levels. This second new observation is a further compelling
indication as to the real function of the cochlear traveling wave.

http://www.neuroscience-of-music.se/Sohmer.htm


Martin


---------------------------------------------------------------------
Martin Braun
Neuroscience of Music
S-671 95 Klässbol
Sweden
email: nombraun@xxxxxxxxx
web site: http://www.neuroscience-of-music.se/index.htm