Distortion products and backward-traveling waves in nonlinear active models of the cochlea.
Distortion products and backward-traveling waves in nonlinear active models of the cochlea.
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DOI：
10.1121/1.3569700
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发表时间：
2011-05
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影响因子：
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通讯作者：
R. Sisto;A. Moleti;T. Botti;D. Bertaccini;C. Shera
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文献类型：
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作者：
R. Sisto;A. Moleti;T. Botti;D. Bertaccini;C. Shera
这项研究探索了非线性耳蜗模型中畸变产物的现象学，预测了它们沿基底膜的振幅和相位。讨论了畸变产物频率处向后行波的存在，最近测量基底膜振动相位的实验对此提出了质疑。分析了不同建模选择的影响，包括前馈不对称性、微观机械粗糙度和尺度对称性的破坏。实验观察到的基底膜相位的负斜率是通过在各种参数和建模选择下对非线性耳蜗模型进行数值模拟来预测的。在主动模型中，只有当畸变产物源位于观察点的顶端并且镫骨反射率小得不切实际时，才可以通过准线性分析计算和完全非线性数值模拟来预测正相位斜率。这项研究的结果预测，只要源分布在相当宽的耳蜗区域和/或假设相当高的镫骨反射率，就会出现负相位斜率。因此，上述实验与耳蜗力学和畸变产物生成的“经典”模型并不矛盾。
This study explores the phenomenology of distortion products in nonlinear cochlear models, predicting their amplitude and phase along the basilar membrane. The existence of a backward-traveling wave at the distortion-product frequency, which has been recently questioned by experiments measuring the phase of basilar-membrane vibration, is discussed. The effect of different modeling choices is analyzed, including feed-forward asymmetry, micromechanical roughness, and breaking of scaling symmetry. The experimentally observed negative slope of basilar-membrane phase is predicted by numerical simulations of nonlinear cochlear models under a wide range of parameters and modeling choices. In active models, positive phase slopes are predicted by the quasi-linear analytical computations and by the fully nonlinear numerical simulations only if the distortion-product sources are localized apical to the observation point and if the stapes reflectivity is unrealistically small. The results of this study predict a negative phase slope whenever the source is distributed over a reasonably wide cochlear region and/or a reasonably high stapes reflectivity is assumed. Therefore, the above-mentioned experiments do not contradict "classical" models of cochlear mechanics and of distortion-product generation.