Stimulus-frequency-emission group delay: a test of coherent reflection filtering and a window on cochlear tuning.
Stimulus-frequency-emission group delay: a test of coherent reflection filtering and a window on cochlear tuning.
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DOI：
10.1121/1.1557211
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发表时间：
2003-05
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影响因子：
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通讯作者：
C. Shera;J. Guinan
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文献类型：
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作者：
C. Shera;J. Guinan
本文测试并应用了相干反射滤波理论的关键预测来生成反射源耳声发射。该理论预测反射源发射群延迟由基底膜（BM）传递函数峰值时的群延迟决定。使用刺激频率发射 (SFOAE) 群延迟测量，在猫和豚鼠的七个倍频程频率范围内测试了这一预测。与根据已发表的 BM 机械传递函数测量结果计算出的群延迟进行比较，支持了耳蜗基端的理论。基于神经调谐锐度与特征频率 (CF) 的变化对整个频率范围进行的比较表明，预测的关系在耳蜗的最基础 60% 中成立。然而，在耳蜗顶端，测量结果与神经和机械群延迟不一致。这种分歧表明，耳蜗基部和顶端之间的耳蜗力学和/或发射产生机制存在重要差异。对人类在四个八度范围内的测量表明，人类 SFOAE 组延迟大约比猫和豚鼠的同类延迟长 3 倍，但在 CF 中表现出类似的趋势。因此，测量结果揭示了尺度的整体偏差，其形式在所有三个物种中在数量上都相似。使用相干反射滤波理论进行解释，群延迟测量表明行波峰值处的波长随着 CF 的增加而减小，在耳蜗基部中以每倍频程约 25% 的速率减小。这里报告的测量和分析说明了 OAE 测量固有的丰富潜力，可以获取有关基本耳蜗特性（例如调谐）的有价值信息。
This paper tests and applies a key prediction of the theory of coherent reflection filtering for the generation of reflection-source otoacoustic emissions. The theory predicts that reflection-source-emission group delay is determined by the group delay of the basilar-membrane (BM) transfer function at its peak. This prediction is tested over a seven-octave frequency range in cats and guinea pigs using measurements of stimulus-frequency-emission (SFOAE) group delay. A comparison with group delays calculated from published measurements of BM mechanical transfer functions supports the theory at the basal end of the cochlea. A comparison across the whole frequency range based on variations in the sharpness of neural tuning with characteristic frequency (CF) suggests that the predicted relation holds in the basal-most 60% of the cochlea. At the apical end of the cochlea, however, the measurements disagree with neural and mechanical group delays. This disagreement suggests that there are important differences in cochlear mechanics and/or mechanisms of emission generation between the base and apex of the cochlea. Measurements in humans over a four-octave range indicate that human SFOAE group delays are roughly a factor of 3 longer than their counterparts in cat and guinea pig but manifest similar trends across CF. The measurements thus reveal global deviations from scaling whose form appears quantitatively similar in all three species. Interpreted using the theory of coherent reflection filtering, the group delay measurements indicate that the wavelength at the peak of the traveling wave decreases with increasing CF at a rate of roughly 25% per octave in the base of the cochlea. The measurements and analysis reported here illustrate the rich potential inherent in OAE measurements for obtaining valuable information about basic cochlear properties such as tuning.