Re: mechanical cochlear model

[Martin Braun <nombraun@xxxxxxxxx>]

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


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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