THE ORIGIN OF PERIODICITY IN THE SPECTRUM OF EVOKED OTOACOUSTIC EMISSIONS
THE ORIGIN OF PERIODICITY IN THE SPECTRUM OF EVOKED OTOACOUSTIC EMISSIONS
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DOI：
10.1121/1.413320
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发表时间：
1995-10-01
影响因子：
2.4
通讯作者：
SHERA, CA
中科院分区：
文献类型：
--
作者：
ZWEIG, G;SHERA, CA
诱发耳声发射的当前模型解释了其频谱中的显著周期性，表明它起源于耳蜗力学中相应的空间反射对前向行波的反射。虽然灵长类耳蜗解剖学的测量没有发现这种现象，但它们确实表明外毛细胞的排列相当不规则。有人建议，诱发发射起源于通过一种新的反射机制，在不均匀，无序介质中的布拉格散射的模拟。向前传播的波反射了柯替氏器微观力学中的随机不规则性。行波的高而宽的波峰定义了相干反射的局部区域，当频率单调变化时，该区域沿着柯替氏器扫过。相干散射发生在峰值内的不规则处，其空间周期等于行波波长的一半。净反射波的相位随频率以由行波在其峰值区域的波长确定的速率均匀地旋转。后向行波和刺激音之间的干扰产生了观察到的光谱周期性。耳道测量与耳蜗力学有关，假设中耳的传输特性随频率变化缓慢，与发射谱中的振荡相比。耳蜗力学在低声级下与诱发发射的频率依赖性之间的关系对于耳蜗力学的一维模型是精确的。在松鼠猴的基底膜运动的测量被用来预测其发射的光谱特性。相反，诱发耳声发射的非侵入性测量用于预测人类行波峰值的宽度和波长。(C)1995年美国声学学会。
Current models of evoked otoacoustic emissions explain the striking periodicity in their frequency spectra by suggesting that it originates through the reflection of forward-traveling waves by a corresponding spatial corrugation in the mechanics of the cochlea. Although measurements of primate cochlear anatomy fmd no such corrugation, they do indicate a considerable irregularity in the arrangement of outer hair cells. It is suggested that evoked emissions originate through a novel reflection mechanism, representing an analogue of Bragg scattering in nonuniform, disordered media. Forward-traveling waves reflect off random irregularities in the micromechanics of the organ of Corti. The tall, broad peak of the traveling wave defines a localized region of coherent reflection that sweeps along the organ of Corti as the frequency is varied monotonically. Coherent scattering occurs off irregularities within the peak with spatial period equal to half the wavelength of the traveling wave. The phase of the net reflected wave rotates uniformly with frequency at a rate determined by the wavelength of the traveling wave in the legion of its peak. Interference between the backward-traveling wave and the stimulus tone creates the observed spectral periodicity. Ear-canal measurements are related to cochlear mechanics by assuming that the transfer characteristics of the middle ear vary slowly with frequency compared to oscillations in the emission spectrum The relationship between cochlear mechanics at low sound levels and the frequency dependence of evoked emissions is made precise for one-dimensional models of cochlear mechanics. Measurements of basilar-membrane motion in the squirrel monkey are used to predict the spectral characteristics of their emissions. And conversely, noninvasive measurements of evoked otoacoustic emissions are used to predict the width and wavelength of the peak of the traveling wave in humans. (C) 1995 Acoustical Society of America.