Determinants of High-frequency Sensitivity in the Bird
In two previous publications (Gummer et al., 1986, 1987) we reported the presence of anti-resonances in the middle-ear transmission function of the pigeon. The anti-resonances were often associated with phase lags of up to 2 cycles at 11 kHz, which were so excessive that basilar membrane (BM) motion recorded in the basal region of the basilar papilla (BP) appeared to lead columella footplate (CFP) motion over an extended frequency range. In this paper we report on the results of experiments which lead us to the conclusion that since travelling waves cannot be launched on the pigeon BM above 6 kHz, the anti-resonances are the result of reflection of incident energy at the basal end of the BM back to the CFP so that the nett volume velocity of the CFP into scala vestibuli vanishes. This proposal may provide an important physical principle for defining the limit of high-frequency sensitivity.
KeywordsTympanic Membrane Basilar Membrane Basilar Papilla Human Cochlea Basilar Membrane Response
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- Gummer, A.W., Smolders, J.W.Th. and Klinke, R. (1986) The mechanics of the basilar membrane and middle ear in the pigeon. In: Peripheral Auditory Mechanisms (Eds: Allen, J.B., Hall, J.L., Hubbard, A., Neely, S.T. and Tubis, A.) Springer-Verlag, Berlin, Heidelberg, New York, Tokyo, pp. 81–88.Google Scholar