Pedersen Benjamin, Ellermeier Wolfgang
Sound Quality Research Unit (SQRU), Department of Acoustics, Aalborg University, Fredrik Bajers Vej 7-B5, 9220 Aalborg Ost, Denmark.
J Acoust Soc Am. 2008 Feb;123(2):963-72. doi: 10.1121/1.2822883.
To determine how listeners weight different portions of the signal when integrating level information, they were presented with 1-s noise samples the levels of which randomly changed every 100 ms by repeatedly, and independently, drawing from a normal distribution. A given stimulus could be derived from one of two such distributions, a decibel apart, and listeners had to classify each sound as belonging to the "soft" or "loud" group. Subsequently, logistic regression analyses were used to determine to what extent each of the ten temporal segments contributed to the overall judgment. In Experiment 1, a nonoptimal weighting strategy was found that emphasized the beginning, and, to a lesser extent, the ending of the sounds. When listeners received trial-by-trial feedback, however, they approached equal weighting of all stimulus components. In Experiment 2, a spectral change was introduced in the middle of the stimulus sequence, changing from low-pass to high-pass noise, and vice versa. The temporal location of the stimulus change was strongly weighted, much as a new onset. These findings are not accounted for by current models of loudness or intensity discrimination, but are consistent with the idea that temporal weighting in loudness judgments is driven by salient events.
为了确定听众在整合响度信息时如何权衡信号的不同部分，向他们呈现1秒的噪声样本，其响度每100毫秒通过从正态分布中重复且独立地抽取而随机变化。给定的刺激可以从两个这样的分布之一中得出，相差1分贝，听众必须将每个声音分类为属于“柔和”或“响亮”组。随后，使用逻辑回归分析来确定十个时间片段中的每一个对整体判断的贡献程度。在实验1中，发现了一种非最优的加权策略，该策略强调声音的开头，在较小程度上强调声音的结尾。然而，当听众逐次试验地收到反馈时，他们对所有刺激成分的加权接近相等。在实验2中，在刺激序列的中间引入了频谱变化，从低通噪声变为高通噪声，反之亦然。刺激变化的时间位置被强烈加权，就像一个新的起始点一样。当前的响度或强度辨别模型无法解释这些发现，但与响度判断中的时间加权由显著事件驱动的观点一致。
