Martin B A, Boothroyd A
Program in Speech and Hearing Sciences, Graduate Center, City University of New York, New York 10036, USA.
J Acoust Soc Am. 2000 Apr;107(4):2155-61. doi: 10.1121/1.428556.
The acoustic change complex (ACC) is a scalp-recorded negative-positive voltage swing elicited by a change during an otherwise steady-state sound. The ACC was obtained from eight adults in response to changes of amplitude and/or spectral envelope at the temporal center of a three-formant synthetic vowel lasting 800 ms. In the absence of spectral change, the group mean waveforms showed a clear ACC to amplitude increments of 2 dB or more and decrements of 3 dB or more. In the presence of a change of second formant frequency (from perceived /u/ to perceived /i/), amplitude increments increased the magnitude of the ACC but amplitude decrements had little or no effect. The fact that the just detectable amplitude change is close to the psychoacoustic limits of the auditory system augurs well for the clinical application of the ACC. The failure to find a condition under which the spectrally elicited ACC is diminished by a small change of amplitude supports the conclusion that the observed ACC to a change of spectral envelope reflects some aspect of cortical frequency coding. Taken together, these findings support the potential value of the ACC as an objective index of auditory discrimination capacity.
听觉变化复合体（ACC）是在稳态声音期间的变化所引发的一种头皮记录的正负电压波动。ACC是从8名成年人对一个持续800毫秒的三共振峰合成元音的时间中心处的幅度和/或频谱包络变化的反应中获得的。在没有频谱变化的情况下，群体平均波形显示出对2分贝或更大的幅度增量以及3分贝或更大的幅度减量有清晰的ACC。在第二共振峰频率发生变化（从感知的/u/到感知的/i/）时，幅度增量增加了ACC的幅度，但幅度减量几乎没有影响或没有影响。刚好可检测到的幅度变化接近听觉系统的心理声学极限这一事实，对于ACC的临床应用来说是个好兆头。未能找到一种情况，即频谱引发的ACC会因幅度的微小变化而减弱，这支持了以下结论：观察到的对频谱包络变化的ACC反映了皮层频率编码的某些方面。综上所述，这些发现支持了ACC作为听觉辨别能力客观指标的潜在价值。
