Phillips Dennis P, Carmichael Martha E, Hall Susan E
Hearing Research Laboratory, Department of Psychology, Dalhousie University, 1355 Oxford Street, Halifax, NS, Canada B3H 4J1.
Hear Res. 2006 Jan;211(1-2):96-102. doi: 10.1016/j.heares.2005.10.005. Epub 2005 Nov 23.
Phillips and Hall [Psychophysical evidence for adaptation of central auditory processors for interaural differences in time and level, Hear. Res., 202 (2005) 188-199.] recently described the frequency-specific, selective adaptation of perceptual channels for interaural differences in level (ILD) and time (ITD). Psychometric functions for laterality based on ITD or ILD were obtained before and after exposure to adaptor tones of two frequencies presented alternately and highly lateralized to opposite sides. Following adaptation, points of perceived centrality (PPCs) were displaced towards the sides of the adaptor tones, and in opposite directions for the two frequencies. That is, laterality judgements showed a shift away from the adapted side, particularly for test cue values near the middle of the range. These data were congruent with a two-channel, opponent-process model of sound laterality coding. The present study used the same general paradigm to explore the independence of perceptual ITD and ILD processing. Psychometric functions for laterality based on ITD or ILD were obtained for each of two frequencies concurrently, before and after exposure to adaptor tones lateralized using the complementary cue. Once again, PPCs derived from the psychometric functions were displaced towards the sides of the adaptor tones, consistent with an opponent-process account of sound laterality coding. The size of the adaptation effect was at least as great as that described in the earlier study. Thus, a quarter cycle ITD adapting stimulus effected a 3 dB shift in the mean ILD-based PPC, and a 12 dB ILD adapting stimulus effected a 100 micros shift in the mean ITD-based PPC. These data offer new evidence concerning interaction in the processing of ITDs and ILDs.
菲利普斯和霍尔[《中枢听觉处理器对耳间时间和强度差异的适应性的心理物理学证据》，《听觉研究》，202卷（2005年），第188 - 199页]最近描述了感知通道对耳间强度差异（ILD）和时间差异（ITD）的频率特异性、选择性适应。在交替呈现两个频率且高度偏向相反侧的适应音之前和之后，获得了基于ITD或ILD的侧向性心理测量函数。适应后，感知中心度点（PPCs）向适应音的方向偏移，且两个频率的偏移方向相反。也就是说，侧向性判断显示出远离适应侧的偏移，特别是对于接近范围中间的测试线索值。这些数据与声音侧向性编码的双通道对立过程模型一致。本研究使用相同的一般范式来探究感知ITD和ILD处理的独立性。在使用互补线索进行侧向化的适应音暴露之前和之后，同时针对两个频率中的每一个获得基于ITD或ILD的侧向性心理测量函数。同样，从心理测量函数得出的PPCs向适应音的方向偏移，这与声音侧向性编码的对立过程解释一致。适应效应的大小至少与早期研究中描述的一样大。因此，一个四分之一周期的ITD适应刺激使基于ILD的平均PPC产生了3 dB的偏移，一个12 dB的ILD适应刺激使基于ITD的平均PPC产生了100微秒的偏移。这些数据提供了关于ITD和ILD处理中相互作用的新证据。
