Lutfi Robert A, Liu Ching-Ju, Stoelinga Christophe
Department of Communicative Disorders, Auditory Behavioral Research Lab, University of Wisconsin, Madison, Wisconsin 53706, USA.
J Acoust Soc Am. 2008 Dec;124(6):3784-92. doi: 10.1121/1.2998767.
Impact sounds were synthesized according to standard textbook equations given for the motion of simply supported, metal plates. In a two-interval, forced-choice procedure, highly practiced listeners identified from these sounds a predefined class of target plates based on their particular material and geometric properties. The effects of two factors on identification were examined: the relative level of partials comprising the sounds and the relative amount of information (given as the difference in d(')) each partial provided for identification. In different conditions one factor was fixed while the other either increased or decreased with frequency. The effect on listener identification in each case was determined from a logistic discriminant analysis of trial-by-trial responses, yielding a vector of listener decision weights on the frequency and decay of individual partials. The weights increased proportionally with relative level, but were largely uninfluenced by relative information content--a result exactly opposite to that expected from a maximum-likelihood observer. The dominant effect of relative level was replicated for other sound sources (clamped bars and stretched membranes) and was not diminished by randomizing the relative level of partials across trials. The results are taken to underscore the importance of relative level in the identification of rudimentary sound sources.
撞击声是根据用于简支金属板运动的标准教科书公式合成的。在一个两区间的强制选择程序中，训练有素的听众根据这些声音，依据特定的材料和几何特性识别出预定义的一类目标板。研究了两个因素对识别的影响：组成声音的分音的相对电平，以及每个分音为识别提供的相对信息量（以d(')的差异表示）。在不同条件下，一个因素固定，另一个因素则随频率增加或减少。每种情况下对听众识别的影响是通过对逐次试验反应进行逻辑判别分析来确定的，得出听众对各个分音的频率和衰减的决策权重向量。权重与相对电平成比例增加，但在很大程度上不受相对信息量的影响——这一结果与最大似然观察者的预期完全相反。相对电平的主导效应在其他声源（夹紧杆和拉伸膜）中也得到了重现，并且通过在试验中随机化分音的相对电平也没有减弱。这些结果强调了相对电平在基本声源识别中的重要性。
