Young E D, Sachs M B
J Acoust Soc Am. 1979 Nov;66(5):1381-1403. doi: 10.1121/1.383532.
This paper is concerned with the representation of the spectra of synthesized steady-state vowels in the temporal aspects of the discharges of auditory-nerve fibers. The results are based on a study of the responses of large numbers of single auditory-nerve fibers in anesthetized cats. By presenting the same set of stimuli to all the fibers encountered in each cat, we can directly estimate the population response to those stimuli. Period histograms of the responses of each unit to the vowels were constructed. The temporal response of a fiber to each harmonic component of the stimulus is taken to be the amplitude of the corresponding component in the Fourier transform of the unit's period histogram. At low sound levels, the temporal response to each stimulus component is maximal among units with CFs near the frequency of the component (i.e., near its place). Responses to formant components are larger than responses to other stimulus components. As sound level is increased, the responses to the formants, particularly the first formant, increase near their places and spread to adjacent regions, particularly toward higher CFs. Responses to nonformant components, exept for harmonics and intermodulation products of the formants (2F1,2F2,F1 + F2, etc), are suppressed; at the highest sound levels used (approximately 80 dB SPL), temporal responses occur almost exclusively at the first two or three formants and their harmonics and intermodulation products. We describe a simple calculation which combines rate, place, and temporal information to provide a good representation of the vowels' spectra, including a clear indication of at least the first two formant frequencies. This representation is stable with changes in sound level at least up to 80 dB SPL; its stability is in sharp contrast to the behavior of the representation of the vowels' spectra in terms of discharge rate which degenerates at stimulus levels within the conversational range.
本文关注合成稳态元音的频谱在听神经纤维放电时间特性方面的表现。研究结果基于对麻醉猫大量单根听神经纤维反应的研究。通过向每只猫中遇到的所有纤维呈现同一组刺激，我们可以直接估计这些刺激的群体反应。构建了每个单元对元音反应的周期直方图。纤维对刺激每个谐波成分的时间反应被视为该单元周期直方图傅里叶变换中相应成分的幅度。在低声强水平时，对每个刺激成分的时间反应在特征频率（CF）接近该成分频率（即接近其位置）的单元中最大。对共振峰成分的反应大于对其他刺激成分的反应。随着声强增加，对共振峰，尤其是第一共振峰的反应在其位置附近增加并扩展到相邻区域，特别是向更高的CF扩展。对非共振峰成分（除了共振峰的谐波和互调产物（2F1、2F2、F1 + F2等））的反应受到抑制；在使用的最高声强水平（约80 dB SPL）下，时间反应几乎仅出现在前两三个共振峰及其谐波和互调产物处。我们描述了一种简单的计算方法，它结合了发放率、位置和时间信息，以很好地呈现元音的频谱，包括至少清晰指示前两个共振峰频率。这种呈现方式在声强至少达到80 dB SPL的变化中是稳定的；其稳定性与在对话范围内刺激水平下元音频谱以发放率表示时的行为形成鲜明对比，后者会退化。
