MRC Cognition & Brain Sciences Unit, 15 Chaucer Rd., Cambridge, CB2 7EF, UK.
Cochlear Ltd., 13059 E. Peakview Avenue, Centennial, CO, 80111, USA.
J Assoc Res Otolaryngol. 2012 Apr;13(2):159-171. doi: 10.1007/s10162-011-0305-0. Epub 2011 Dec 8.
When a pure tone or low-numbered harmonic is presented to a listener, the resulting travelling wave in the cochlea slows down at the portion of the basilar membrane (BM) tuned to the input frequency due to the filtering properties of the BM. This slowing is reflected in the phase of the response of neurons across the auditory nerve (AN) array. It has been suggested that the auditory system exploits these across-channel timing differences to encode the pitch of both pure tones and resolved harmonics in complex tones. Here, we report a quantitative analysis of previously published data on the response of guinea pig AN fibres, of a range of characteristic frequencies, to pure tones of different frequencies and levels. We conclude that although the use of across-channel timing cues provides an a priori attractive and plausible means of encoding pitch, many of the most obvious metrics for using that cue produce pitch estimates that are strongly influenced by the overall level and therefore are unlikely to provide a straightforward means for encoding the pitch of pure tones.
当一个纯音或低阶谐波被呈现给听众时，由于基底膜（BM）的滤波特性，在与输入频率调谐的基底膜部分，行波在耳蜗中的传播速度会减慢。这种减慢反映在听觉神经（AN）阵列中神经元反应的相位上。有人认为，听觉系统利用这些跨通道的时间差异来编码纯音和复音中解析谐波的音高。在这里，我们对豚鼠听觉神经纤维对不同频率和水平的纯音反应的先前发表数据进行了定量分析。我们的结论是，尽管使用跨通道时间线索提供了一种有吸引力和合理的编码音调的方法，但许多使用该线索的最明显指标产生的音调估计受到整体水平的强烈影响，因此不太可能为编码纯音的音调提供直接手段。
