Subject: Re: Traveling waves or resonance? From: Martin Braun <nombraun(at)TELIA.COM> Date: Wed, 20 Oct 2004 14:50:03 +0200Richard F. Lyon wrote on October 20: > Ren's statement that "In sensitive cochleae, the cochlear partition > vibration at a given location shows a maximum response to a stimulus > at the CF, falls off quickly at frequencies above or below the CF, > and forms a sharp peak in magnitude transfer functions" has been > interpreted by some as saying that the response is fairly "symmetric" > about CF. But the data do not show that, as Fig. 4C makes most > clear. Dick, Fig. 4C is not the right one to explore the symmetry question. The most straightforward figure in this respect is Fig. 1A, as all unbiased readers will see immediately: Full text article: http://www.pnas.org/cgi/content/full/99/26/17101 Figure 1 only: http://www.pnas.org/cgi/content/full/99/26/17101/F1 Here we can see that the curves for 10, 20, 30, 40, and 50 dB show symmetrical peaks. From 60 to 90 dB then, they are increasingly asymmetrical with longer and shallower slopes towards the basal side. This figure accurately reflects a condition of local resonance up to ca 60 dB, and an additional basilar membrane traveling wave above ca 60 dB. All this has been discussed in detail on the Cochlea List: http://mimosa1.incubator.uiuc.edu/pipermail/cochlea/2002-December/001546.html http://mimosa1.incubator.uiuc.edu/pipermail/cochlea/2002-December/001550.html It is no accident, and not based on the errors of hundreds of readers, that this paper is widely discussed as a turning point in inner ear research. Martin ---------------------------- Martin Braun Neuroscience of Music S-671 95 Klässbol Sweden web site: http://w1.570.telia.com/~u57011259/index.htm