Subject: Re: mechanical cochlear model From: Martin Braun <nombraun@xxxxxxxx> Date: Wed, 2 Jun 2010 11:13:05 +0200 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>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 --------------------------------------------------------------------- Martin Braun Neuroscience of Music S-671 95 Klässbol Sweden email: nombraun@xxxxxxxx web site: http://www.neuroscience-of-music.se/index.htm ----- Original Message ----- From: "Martin Braun" <nombraun@xxxxxxxx> To: <AUDITORY@xxxxxxxx> 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@xxxxxxxx web site: http://www.neuroscience-of-music.se/index.htm