Palmer A R, Winter I M, Darwin C J
J Acoust Soc Am. 1986 Jan;79(1):100-13. doi: 10.1121/1.393633.
We have recorded the responses of fibers in the cochlear nerve and cells in the cochlear nucleus of the anesthetized guinea pig to synthetic vowels [i], [a], and [u] at 60 and 80 dB SPL. Histograms synchronized to the pitch period of the vowel were constructed, and locking of the discharge to individual harmonics was estimated from these by Fourier transformation. In cochlear nerve fibers from the guinea pig, the responses were similar in all respects to those previously described for the cat. In particular, the average-localized-synchronized-rate functions (ALSR), computed from pooled data, had well-defined peaks corresponding to the formant frequencies of the three vowels at both sound levels. Analysis of the components dominating the discharge could also be used to determine the voice pitch and the frequency of the first formants. We have computed similar population measures over a sample of primarylike cochlear nucleus neurons. In these primarylike cochlear nucleus cell responses, the locking to the higher-frequency formants of the vowels is weaker than in the nerve. This results in a severe degradation of the peaks in the ALSR function at the second and third formant frequencies at least for [i] and [u]. This result is somewhat surprising in light of the reports that primarylike cochlear nucleus cells phaselock, as well as do cochlear nerve fibers.
我们记录了麻醉豚鼠的耳蜗神经纤维和耳蜗核细胞对60和80 dB SPL的合成元音[i]、[a]和[u]的反应。构建了与元音基音周期同步的直方图，并通过傅里叶变换从这些直方图中估计放电对各个谐波的锁定情况。在豚鼠的耳蜗神经纤维中，其反应在各方面都与先前描述的猫的反应相似。特别是，从汇总数据计算得到的平均局部同步率函数（ALSR）在两个声级下都有对应于三个元音共振峰频率的明确峰值。对主导放电的成分进行分析也可用于确定语音音高和第一共振峰的频率。我们在一组初级类耳蜗核神经元样本上计算了类似的总体测量值。在这些初级类耳蜗核细胞的反应中，对元音高频共振峰的锁定比在神经中弱。这至少在[i]和[u]的情况下导致ALSR函数在第二和第三共振峰频率处的峰值严重退化。鉴于有报道称初级类耳蜗核细胞与耳蜗神经纤维一样能进行锁相，这一结果有些令人惊讶。
