Wightman F L, Kistler D J
Department of Psychology and Waisman Center, University of Wisconsin-Madison 53705, USA.
J Acoust Soc Am. 1997 Feb;101(2):1050-63. doi: 10.1121/1.418029.
Research reported during the past few decades has revealed the importance for human sound localization of the so-called "monaural spectral cues." These cues are the result of the direction-dependent filtering of incoming sound waves accomplished by the pinnae. One point of view about how these cues are extracted places great emphasis on the spectrum of the received sound at each ear individually. This leads to the suggestion that an effective way of studying the influence of these cues is to measure the ability of listeners to localize sounds when one of their ears is plugged. Numerous studies have appeared using this monaural localization paradigm. Three experiments are described here which are intended to clarify the results of the previous monaural localization studies and provide new data on how monaural spectral cues might be processed. Virtual sound sources are used in the experiments in order to manipulate and control the stimuli independently at the two ears. Two of the experiments deal with the consequences of the incomplete monauralization that may have contaminated previous work. The results suggest that even very low sound levels in the occluded ear provide access to interaural localization cues. The presence of these cues complicates the interpretation of the results of nominally monaural localization studies. The third experiment concerns the role of prior knowledge of the source spectrum, which is required if monaural cues are to be useful. The results of this last experiment demonstrate that extraction of monaural spectral cues can be severely disrupted by trial-to-trial fluctuations in the source spectrum. The general conclusion of the experiments is that, while monaural spectral cues are important, the monaural localization paradigm may not be the most appropriate way to study their role.
过去几十年间报告的研究揭示了所谓“单耳频谱线索”对人类声音定位的重要性。这些线索是耳廓对传入声波进行方向依赖性滤波的结果。关于如何提取这些线索的一种观点非常强调每只耳朵接收到的声音频谱。这就引出了一个观点，即研究这些线索影响的一种有效方法是测量听众在一只耳朵被堵住时定位声音的能力。已经出现了许多使用这种单耳定位范式的研究。这里描述了三个实验，旨在阐明先前单耳定位研究的结果，并提供关于单耳频谱线索可能如何被处理的新数据。实验中使用虚拟声源以便在两只耳朵处独立地操纵和控制刺激。其中两个实验探讨了可能影响先前研究的不完全单耳化的后果。结果表明，即使被阻塞耳朵中的声音水平非常低，也能获取双耳间的定位线索。这些线索的存在使名义上单耳定位研究结果的解释变得复杂。第三个实验关注源频谱先验知识的作用，单耳线索若要有用就需要这种知识。最后这个实验的结果表明，源频谱的逐次试验波动会严重干扰单耳频谱线索的提取。实验的总体结论是，虽然单耳频谱线索很重要，但单耳定位范式可能不是研究其作用的最恰当方式。
