Wasn't v. Helmholtz right? (Eckard Blumschein )

Subject: Wasn't v. Helmholtz right?
From:    Eckard Blumschein  <Eckard.Blumschein(at)E-TECHNIK.UNI-MAGDEBURG.DE>
Date:    Mon, 22 May 2000 13:54:04 +0200

Dear list, The recent edition of Auditory Perception by Richard M. Warren provides an excellent review of Mechanics for Stimulation within the Inner Ear. Unfortunately, the author preferred to leave some conclusions and possibly some notorious errors to the reader. He wrote correctly: The speed of sound in the cochlear liquids is very much faster ((than velocity of the traveling wave)), about 1,600 m/sec (this difference is of significance in determining whether the traveling wave or the sound pressure is the stimulus for receptor cell transduction...). He did not, however, mention the question whether or not the traveling wave is the result of energy transmission basilar from base to apex inside basilar membrane or it might rather be an epi-phenomenon, i.e. an attendant symptom of local resonance. Referring to Lewis, Leverence, and Bialek (1985), and also to de Boer and Nutall (1996), Dancer, Avan, and Magnan (1997) tried to belittle this discrepancy by calling the traveling wave a leitmotiv. Recio, Rich, Narayan, and Ruggero (1998) rejected this point of view. Can anybody point me to the final outcome of that discussion? Possibly, I am simply not yet aware of the latest news since I did neither attend a concerning conference in Japan last year nor the ARO meeting this year. It is my gut feeling that v. Helmholtz was pretty right with his idea of local resonance. Otherwise, I was wrong with my speculations on physiology of the inner ear of some animals, explanation of equivalence of net latency and 1/CF, problems with understanding of DPOAE, etc. I also realized evidence for the longitudinal coupling being fairly weak. Local resonance does neither exclude the appearance of a traveling wave nor the application of a modified transmission line model (with a nearly common upper potential along the whole length). I additionally imagine an additional oscillating motion back and forth in radial direction due to motility of the outer hair cells. Radial component of velocity was reported ten times larger than the longitudinal one. Once again, may I ask for hints to the ultimate elucidation? As Dancer et al. stated, the two positions should have implications in signal processing. Suggesting that psychoacoustics may be the touchstone for theories, I would be curious if it will really be possible to compensate for the traveling wave delay. Thank you very much, Dr. Eckard Blumschein Inst. of Electronics, Signal Processing, and Telecommunication Otto von Guericke Univ. Magdeburg, GERMANY

This message came from the mail archive
maintained by:
DAn Ellis <dpwe@ee.columbia.edu>
Electrical Engineering Dept., Columbia University