Tollin D J, Henning G B
Department of Experimental Psychology, University of Oxford, United Kingdom.
J Acoust Soc Am. 1999 Feb;105(2 Pt 1):838-49. doi: 10.1121/1.426273.
The lateralization of clicks and their "echoes" was investigated with a view to determining the role of spectral characteristics in lateralization. Lateralization-discrimination performance was measured in a number of two-interval, two-alternative forced-choice experiments using three pairs of binaural clicks designed to elucidate how spectral cues are used in lateralization. The stimulus in one observation interval comprised a diotic click followed, after the interclick interval (ICI), by a dichotic click with either (1) an interaural time delay or (2) an interaural amplitude difference. The dichotic click was in turn followed, after an ICI of the same size, by another diotic click. In the second observation interval, the signals to the two ears were interchanged. The stimulus has the property that the signals delivered to the two ears had either (1) identical energy-density spectra but nonzero interaural-phase differences (IPDs) or (2) zero IPDs but nonidentical energy-density spectra. Under certain circumstances, observers perceived these stimuli as arising from the side of the head opposite that which would be predicted from the direction of the interaural cue in the temporal waveform. Joint consideration of the psychophysical data and the spectral characteristics of the stimuli strongly suggest a spectral "dominance region" for lateralization near 750 Hz, observers' lateralization performance was determined predominantly by the IPD cues from this region. In general, the results demonstrate that echoes of transients that arrive within about 2-3 ms of an initial transient are not suppressed, but have a substantial effect on lateralization through their contribution to the resultant spectral characteristics. The results contradict models that represent the precedence effect as the temporary suppression or inhibition of directional information in echoes over 2-3 ms after an initial transient.
为了确定频谱特征在声源定位中的作用，对滴答声及其“回声”的声源定位进行了研究。在一系列两间隔、二选一的强制选择实验中，测量了声源定位辨别性能，实验使用了三对双耳滴答声，旨在阐明频谱线索在声源定位中的使用方式。在一个观察间隔中的刺激包括一个双耳同时呈现的滴答声，在滴答声间隔（ICI）之后，接着是一个双耳不同呈现的滴答声，其具有以下两种情况之一：（1）耳间时间延迟，或（2）耳间幅度差异。在相同大小的ICI之后，双耳不同呈现的滴答声又接着是另一个双耳同时呈现的滴答声。在第二个观察间隔中，传至两耳的信号相互交换。该刺激具有这样的特性，即传至两耳的信号要么（1）具有相同的能量密度谱但非零的耳间相位差（IPD），要么（2）IPD为零但能量密度谱不同。在某些情况下，观察者会将这些刺激感知为来自头部与根据时间波形中耳间线索方向所预测的相反一侧。对心理物理学数据和刺激的频谱特征的联合考虑强烈表明，在750Hz附近存在一个用于声源定位的频谱“优势区域”，观察者的声源定位性能主要由该区域的IPD线索决定。一般来说，结果表明，在初始瞬态大约2 - 3毫秒内到达的瞬态回声不会被抑制，而是通过它们对合成频谱特征的贡献对声源定位产生重大影响。这些结果与将优先效应表示为初始瞬态后2 - 3毫秒以上回声中方向信息的临时抑制的模型相矛盾。
