Shinn-Cunningham B G, Zurek P M, Durlach N I, Clifton R K
Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge 02139, USA.
J Acoust Soc Am. 1995 Jul;98(1):164-71. doi: 10.1121/1.413752.
This paper concerns the extent to which the precedence effect is observed when leading and lagging sounds occupy different spectral regions. Subjects, listening under headphones, were asked to match the intracranial lateral position of an acoustic pointer to that of a test stimulus composed of two binaural noise bursts with asynchronous onsets, parametrically varied frequency content, and different interaural delays. The precedence effect was measured by the degree to which the interaural delay of the matching pointer was independent of the interaural delay of the lagging noise burst in the test stimulus. The results, like those of Blauert and Divenyi [Acustica 66, 267-274 (1988)], show an asymmetric frequency effect in which the lateralization influence of a lagging high-frequency burst is almost completely suppressed by a leading low-frequency burst, whereas a lagging low-frequency burst is weighted equally with a leading high-frequency burst. This asymmetry is shown to be the result of an inherent low-frequency dominance that is seen even with simultaneous bursts. When this dominance is removed (by attenuating the low-frequency burst) the precedence effect operates with roughly equal strength both upward and downward in frequency. Within the scope of the current study (with lateralization achieved through the use of interaural time differences alone, stimuli from only two frequency bands, and only three subjects performing in all experiments), these results suggest that the precedence effect arises from a fairly central processing stage in which information is combined across frequency.
本文关注的是当先导音和滞后音占据不同频谱区域时，优先效应的表现程度。要求受试者佩戴耳机聆听，将一个声学指针的颅内横向位置与一个测试刺激的位置相匹配，该测试刺激由两个双耳噪声突发组成，其起始异步、频率成分参数可变且耳间延迟不同。优先效应通过匹配指针的耳间延迟与测试刺激中滞后噪声突发的耳间延迟的独立程度来衡量。结果与布劳尔特和迪韦尼伊[《声学学报》66, 267 - 274 (1988)]的结果一样，显示出一种不对称频率效应，即滞后高频突发的侧向化影响几乎完全被先导低频突发抑制，而滞后低频突发与先导高频突发的权重相等。这种不对称被证明是即使在同时突发时也存在的固有低频优势的结果。当这种优势被消除（通过衰减低频突发）时，优先效应在频率上向上和向下的作用强度大致相等。在当前研究的范围内（通过仅使用耳间时间差实现侧向化，仅来自两个频带的刺激，且所有实验仅有三名受试者参与），这些结果表明优先效应源于一个相当中枢的处理阶段，在该阶段信息在频率上进行整合。
