a resonance approach to cochlear mechanics共振方法耳蜗力学.pdfVIP

A Resonance Approach to Cochlear Mechanics Andrew Bell* Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, Canberra, Australia Abstract Background: How does the cochlea analyse sound into its component frequencies? In the 1850s Helmholtz thought it ´ ´ occurred by resonance, whereas a century later Bekesy’s work indicated a travelling wave. The latter answer seemed to settle the question, but with the discovery in 1978 that the cochlea emits sound, the mechanics of the cochlea was back on the drawing board. Recent studies have raised questions about whether the travelling wave, as currently understood, is adequate to explain observations. Approach: Applying basic resonance principles, this paper revisits the question. A graded bank of harmonic oscillators with cochlear-like frequencies and quality factors is simultaneously excited, and it is found that resonance gives rise to similar frequency responses, group delays, and travelling wave velocities as observed by experiment. The overall effect of the group delay gradient is to produce a decelerating wave of peak displacement moving from base to apex at characteristic travelling wave speeds. The extensive literature on chains of coupled oscillators is considered, and the occurrence of travelling waves, pseudowaves, phase plateaus, and forced resonance in such systems is noted. Conclusion and significance: This alternative approach to cochlear mechanics shows that a travelling wave can simply arise as an apparently moving amplitude peak which passes along a bank of resonators without carrying energy. This highlights the possible role of the fast pressure wave and indicates how phase delays and group delays of a set of driven harmonic