Rhode William S
Department of Physiology, University of Wisconsin, Madison, Wisconsin 53706, USA.
J Acoust Soc Am. 2007 Nov;122(5):2725-37. doi: 10.1121/1.2785034.
Distortion product otoacoustic emissions (DPOAEs) and basilar membrane (BM) vibration were measured simultaneously in the 6-9 kHz region of chinchilla cochleae. BM-Input-Output functions in a two-tone paradigm behaved similarly to DPOAEs for the 2f1-f2 component, nonmonotonic growth with the intensity of the lower frequency primary and a notch in the functions around 60 dB SPL. Ripples in frequency functions occur in both BM and OAE curves as a function of the distortion frequency. Optimum f2/f1 ratios for DPOAE generation are near 1.2. The slope of phase curves indicates that for low f2f1(<1.1) the emission source is the place location while for f2f1>1.1 the relative constancy of the phase function suggests that the place is the nonlinear region of f2, i.e., the wave location. Magnitudes of the DPOAEs increase rapidly above 60 dB SPL suggesting a different source or mechanism at high levels. This is supported by the observation that the high level DPOAE and BM-DP responses remain for a considerable period postmortem.
在灰鼠耳蜗的6-9kHz区域同时测量了畸变产物耳声发射（DPOAE）和基底膜（BM）振动。在双音范式中，BM输入-输出函数对于2f1-f2分量的表现与DPOAE相似，随着低频初级音强度的增加呈非单调增长，并且在60dB SPL左右的函数中有一个凹口。频率函数中的波纹在BM和OAE曲线中均作为畸变频率的函数出现。产生DPOAE的最佳f2/f1比率接近1.2。相位曲线的斜率表明，对于低f2f1（<1.1），发射源是位置点，而对于f2f1>1.1，相位函数的相对恒定表明该位置是f2的非线性区域，即波的位置。DPOAE的幅度在60dB SPL以上迅速增加，表明在高水平时有不同的源或机制。这得到了以下观察结果的支持：高水平的DPOAE和BM-DP反应在死后相当长的一段时间内仍然存在。
