Subject: Re: BM motion From: David Mountain <dcm@xxxxxxxx> Date: Wed, 14 Nov 2007 09:24:54 -0500 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>Conventional traveling-wave theory does account for high-side suppression. In an active cochlea, as the traveling wave approaches its best location, it is amplified over a region basal to the peak. If the suppression tone excites this basal region, it will interfere with the amplification process. For more information on the spatial extent of high-side suppression, see: Javel E, Geisler CD, Ravindran A. Two-tone suppression in auditory nerve of the cat: rate-intensity and temporal analyses J Acoust Soc Am. 1978 Apr;63(4):1093-104. -------------------------------------------------------------------- David C. Mountain, Ph.D. Professor of Biomedical Engineering Boston University 44 Cummington St. Boston, MA 02215 Email: dcm@xxxxxxxx Website: http://www.bu.edu/dbin/bme/faculty/?prof=dcm Phone: (617) 353-4343 FAX: (617) 353-6766 Office: ERB 413 On Wed, 14 Nov 2007, Matt Flax wrote: > Hi list and Richard, > > Travelling waves have no mechanism for high side suppression... > it is simply not possible. > > Clearly in the literature [1] last paragraph for example ... here > is an excerpt : > ... neither models nor experiments have yet answered what > is perhaps the central question of mammalian cochlear > physiology, namely, the origin of the CF specificity of > two-tone suppression and other mechanical nonlinearities. > > I have other references. > > [1] > @xxxxxxxx{Ruggero:1992, > author = {Ruggero, M.A. and Robles, L. and Rich, N.C.}, > title = {Two-tone suppression in the basilar membrane of the cochlea: > mechanical > basis of auditory-nerve rate suppression}, > journal = {Journal of Neurophysiology}, > year = {1992}, > volume = {68}, > pages = {1087-1099}, > number = {4}, > month = {October} > } > > > On Tue, Nov 13, 2007 at 08:22:06PM -0800, Richard F. Lyon wrote: > > No matter how the nonlinearity affects the tone amplitudes, the sum of two > > sinusoids of different frequencies is easily distinguishable from a larger > > single sinusoid, through the temporal pattern, which will be appararent in > > the auditory nerve firing-time patterns, even when both frequencies are > > higher than can be coded by synchrony. > > > > As to the nonlinearity, it shows up clearly in the mechanics, when the OHCs > > are functioning, and it's not hard to see how OHCs in one region can change > > the response to other tones that travel through that region to be localized > > further on; that is, how high-f can suppress low-f if not too much lower. > > The other direction works slightly differently, but the key is that > > different frequencies share the same traveling wave medium that amplifies > > them, so you get suppression. There may yet be mysteries in the > > micromechanical details, but not in the overall functional effect. > > > > Matt, is the "'frequency specificity' mystery" something that you find in > > the literature? Or do you just mean you haven't found a clear enough > > explanation? > > > > Dick > > -- > > ,dPYb,,dPYb, I8 > IP'`YbIP'`Yb I8 http://www.flatmaxstudios.com/ > I8 8II8 8I 88888888 http://www.flatmax.org > I8 8'I8 8' I8 > I8 dP I8 dP ,gggg,gg I8 ,ggg,,ggg,,ggg, ,gggg,gg ,gg, ,gg > I8dP I8dP dP" "Y8I I8 ,8" "8P" "8P" "8, dP" "Y8I d8""8b,dP" > I8P I8P i8' ,8I ,I8, I8 8I 8I 8I i8' ,8I dP ,88" > ,d8b,_,d8b,_,d8, ,d8b,d88b,dP 8I 8I Yb,d8, ,d8b,dP ,dP"Y8, > PI8"888P'"Y8P"Y8888P"`Y8P""Y8P' 8I 8I `YP"Y8888P"`Y8" dP" "Y8 > I8 `8, > I8 `8, > I8 8I Public Projects : > I8 8I http://sourceforge.net/search/?type_of_search=soft&words=mffm > I8, ,8' http://www.psysound.org > "Y8P' >