Subject: Re: Traveling waves or resonance? From: Eckard Blumschein <Eckard.Blumschein(at)E-Technik.Uni-Magdeburg.DE> Date: Mon, 18 Oct 2004 15:01:24 +0200Dear Martin, May I ask you and Martin for not neglecting our common insight that it's overdue to finally bury all theories which assume essential transmission of energy within basilar membrane from base to apex the main principle of hearing? This includes the hydromechanical model by Lighthill alias Lichtenberg as well as all transmission line models. Let's deal with the objection: 'Resonances are generally way too narrow (too sharp and too symmetrical compared to real data or to TW models'. Maybe such objections are justified if we have a too simple idea of local resonance. I am unhappy with the alternative decision between traveling waves or resonance, for several reasons. First of all, a traveling wave phenomenon is observable. It even includes wave propagation inside a finally standing envelope. However, the phenomenon is not really based on lateral wave propagation. For a comparison, look into pertaining figures at http://iesk.et.uni-magdeburg.de/~blumsche/M275 and M277. Notice, what I named 'the natural spectrogram' is distinguished by not relying an any parameter except for attenuation. Nonetheless, it well agrees with shamelessly tweaked models. In M277 I try to explain how coarse cochlear frequency analysis can be an advantage: Perhaps, cochlear frequency analysis is just the first step of an overall autocorrelation. The second (cepstral-like) step of this joint analysis requires enough bandwidth in order to form an auditory image as a spectrally-based time pattern. It is my speculation that such iterative use of simple principles was a starting point for evolution of mammal intelligence. Martin reminded of the older biochemical, i.e. electrical, sensors being subject to tight frequency restrictions. Mammals got superior with their faster mechano-electrical mechanism of preamplification by means of outer hair cells. Regards, Eckard