Goodman Shawn S, Withnell Robert H, Shera Christopher A
Department of Speech and Hearing Sciences, Indiana University, 200 South Jordan Avenue, Bloomington, IN 47405, USA.
Hear Res. 2003 Sep;183(1-2):7-17. doi: 10.1016/s0378-5955(03)00193-x.
Human stimulus-frequency otoacoustic emissions (SFOAEs) evoked by low-level stimuli have previously been shown to have properties consistent with such emissions arising from a linear place-fixed reflection mechanism with SFOAE microstructure thought to be due to a variation in the effective reflectance with position along the cochlea [Zweig and Shera, J. Acoust. Soc. Am. 98 (1995) 2018-2047]. Here we report SFOAEs in the guinea pig obtained using a nonlinear extraction paradigm from the ear-canal recording that show amplitude and phase microstructure akin to that seen in human SFOAEs. Inverse Fourier analysis of the SFOAE spectrum indicates that SFOAEs in the guinea pig are a stimulus level-dependent mix of OAEs arising from linear-reflection and nonlinear-distortion mechanisms. Although the SFOAEs are dominated by OAE generated by a linear-reflection mechanism at low and moderate stimulus levels, nonlinear distortion can dominate some part of, or all of, the emission spectrum at high levels. Amplitude and phase microstructure in the guinea pig SFOAE is evidently a construct of (i). the complex addition of nonlinear-distortion and linear-reflection components; (ii). variation in the effective reflectance with position along the cochlea; and perhaps (iii). the complex addition of multiple intra-cochlear reflections.
先前的研究表明，低强度刺激诱发的人类刺激频率耳声发射（SFOAE）具有的特性与线性位置固定反射机制产生的此类发射一致，SFOAE的微观结构被认为是由于沿耳蜗位置的有效反射率变化所致[茨威格和谢拉，《美国声学学会杂志》98 (1995) 2018 - 2047]。在此，我们报告了在豚鼠中使用非线性提取范式从耳道记录获得的SFOAE，其显示出与人类SFOAE中所见类似的幅度和相位微观结构。对SFOAE频谱进行傅里叶逆分析表明，豚鼠中的SFOAE是由线性反射和非线性失真机制产生的耳声发射的刺激水平依赖性混合。尽管在低和中等刺激水平下，SFOAE主要由线性反射机制产生的耳声发射主导，但在高强度下，非线性失真可在发射频谱的某些部分或全部占主导地位。豚鼠SFOAE中的幅度和相位微观结构显然是以下因素的组合：(i). 非线性失真和线性反射成分的复杂叠加；(ii). 沿耳蜗位置的有效反射率变化；以及可能(iii). 多个耳蜗内反射的复杂叠加。
