| Abstrakt: |
The tectorial membrane (TM) of the mammalian inner ear is considered as a system of weakly bent beams and is modeled by a long flat anisotropic plate with one edge supported by the immovable “limbus,” while the opposite edge rests on top of the outer hair cells (OHC). The cross-sectional eigenfunctions of the tectorial membrane isolated from Corti's organ are calculated. It is shown that, under the condition that the limbal edge is supported, the first eigenfunction has an immovable nodal point near the free edge. If the corresponding eigenfrequency of the tectorial membrane coincides with the fundamental eigenfrequency of the cross section, the middle part of the tectorial membrane moves in phase with the basilar membrane, while its marginal edge moves in the opposite direction. As a consequence, the outer hair cells, connecting the middle line of the basilar membrane with its marginal edge, are subject to altering compressive and stretching forces. Thus, the oscillations of the outer hair cells seem to be merely a forced, “passive” mechanical movement rather than an “active” biological process. Taking into account the shapes of the graphs of the tectorial membrane cross-sectional eigenfunctions provides a possibility of explaining a great deal of various experimental data in a simple and natural way without conjecturing negative damping. Bibliography: 25 titles. |
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