Sharma A, Marsh C M, Dorman M F
Department of Speech and Hearing Science, Arizona State University, Tempe 85287-0102, USA.
J Acoust Soc Am. 2000 Dec;108(6):3030-5. doi: 10.1121/1.1320474.
Auditory evoked potential (AEP) correlates of the neural representation of stimuli along a /ga/-/ka/ and a /ba/-/pa/ continuum were examined to determine whether the voice-onset time (VOT)-related change in the N1 onset response from a single to double-peaked component is a reliable indicator of the perception of voiced and voiceless sounds. Behavioral identification results from ten subjects revealed a mean category boundary at a VOT of 46 ms for the /ga/-/ka/ continuum and at a VOT of 27.5 ms for the /ba/-/pa/ continuum. In the same subjects, electrophysiologic recordings revealed that a single N1 component was seen for stimuli with VOTs of 30 ms and less, and two components (N1' and N1) were seen for stimuli with VOTs of 40 ms and more for both continua. That is, the change in N1 morphology (from single to double-peaked) coincided with the change in perception from voiced to voiceless for stimuli from the /ba/-/pa/ continuum, but not for stimuli from the /ga/-/ka/ continuum. The results of this study show that N1 morphology does not reliably predict phonetic identification of stimuli varying in VOT. These findings also suggest that the previously reported appearance of a "double-peak" onset response in aggregate recordings from the auditory cortex does not indicate a cortical correlate of the perception of voicelessness.
研究了沿/ga/-/ka/和/ba/-/pa/连续体的刺激的神经表征的听觉诱发电位（AEP）相关性，以确定从单峰到双峰成分的N1起始反应中与语音起始时间（VOT）相关的变化是否是浊音和清音感知的可靠指标。十名受试者的行为识别结果显示，/ga/-/ka/连续体的VOT平均类别边界为46毫秒，/ba/-/pa/连续体的VOT平均类别边界为27.5毫秒。在相同的受试者中，电生理记录显示，对于VOT为30毫秒及以下的刺激，可见单个N1成分；对于两个连续体中VOT为40毫秒及以上的刺激，可见两个成分（N1'和N1）。也就是说，对于/ba/-/pa/连续体的刺激，N1形态的变化（从单峰到双峰）与从浊音到清音的感知变化一致，但对于/ga/-/ka/连续体的刺激则不然。本研究结果表明，N1形态不能可靠地预测VOT变化的刺激的语音识别。这些发现还表明，先前报道的听觉皮层总体记录中出现的“双峰”起始反应并不表明清音感知的皮层相关性。
