Sachs M B, Young E D
J Acoust Soc Am. 1979 Aug;66(2):470-9. doi: 10.1121/1.383098.
Responses of large populations of auditory-nerve fibers to synthesized steady-state vowels were recorded in anesthetized cats. Driven discharge rate to vowels, normalized by dividing by saturation rate (estimated from the driven rate to CF tones 50 dB above threshold), was plotted versus fiber CF for a number of vowel levels. For the vowels /I/ and /e/, such rate profiles showed a peak in the region of the first formant and another in the region of the second and third formants, for sound levels below about 70 dB SPL. For /a/ at levels below about 40 dB SPL there are peaks in the region of the first and second formants. At higher levels these peaks disappear for all the vowels because of a combination of rate saturation and two-tone suppression. This must be qualified by saying that rate profiles plotted separately for units with spontaneous rates less than one spike per second may retain peaks at higher levels. Rate versus level functions for units with CFs above the first formant can saturate at rates less than the saturation rate to CF to-es or they can be nonmonotonic; these effects are most likely produced by the same mechanism as that involved in two-tone suppression.
在麻醉猫身上记录了大量听神经纤维对合成稳态元音的反应。将元音的驱动放电率除以饱和率（由高于阈值50 dB的CF音的驱动率估计）进行归一化处理，针对多个元音水平，绘制了驱动放电率与纤维CF的关系图。对于元音 /I/ 和 /e/，在声压级低于约70 dB SPL时，这样的放电率分布图在第一共振峰区域出现一个峰值，在第二和第三共振峰区域出现另一个峰值。对于 /a/，在声压级低于约40 dB SPL时，在第一和第二共振峰区域有峰值。在较高声压级时，由于放电率饱和和双音抑制的共同作用，所有元音的这些峰值都会消失。必须说明的是，对于自发放电率小于每秒一个脉冲的单元单独绘制的放电率分布图，在较高声压级时可能会保留峰值。CF高于第一共振峰的单元的放电率与声压级函数可能在低于CF音饱和率的放电率时达到饱和，或者它们可能是非单调的；这些效应很可能是由与双音抑制相同的机制产生的。
