Lutfi R A, Doherty K A, Oh E
Department of Communicative Disorders, University of Wisconsin, Madison 53706, USA.
J Acoust Soc Am. 1996 Oct;100(4 Pt 1):2258-65. doi: 10.1121/1.417935.
An experiment was conducted to measure the shape of the psychometric function for the discrimination of spectral variance. The stimuli were simultaneous tone complexes comprised of the six octave frequencies from 250 to 8000 Hz. On each presentation the levels of components in dB were drawn independently and at random from one of two normal distributions having identical means but different variances (sigma N = 1 dB, sigma S = 2-10 dB). In the standard two-interval, forced-choice procedure, the listeners' task was to indicate which complex had the greater variance in component level. The shape of the psychometric function for all five listeners was markedly different from that of an observer limited only by additive internal noise. It was consistent with an observer that gives weight to only one or two components in the complex. However, this result was inconsistent with the weighting functions computed from the trial-by-trial data from these listeners. Both measures can be reconciled if it is assumed that listener weights vary from trial to trial, or that decisions are based on the one tone in the complex having the maximum level.
进行了一项实验，以测量用于辨别频谱方差的心理测量函数的形状。刺激是由250至8000赫兹的六个倍频程频率组成的同时性音调复合体。每次呈现时，以分贝为单位的成分水平从具有相同均值但不同方差的两个正态分布之一中独立且随机抽取（标准差N = 1分贝，标准差S = 2 - 10分贝）。在标准的两区间强制选择程序中，听众的任务是指出哪个复合体在成分水平上具有更大的方差。所有五位听众的心理测量函数形状与仅受加性内部噪声限制的观察者的形状明显不同。这与仅对复合体中的一两个成分赋予权重的观察者一致。然而，这一结果与根据这些听众的逐次试验数据计算出的加权函数不一致。如果假设听众的权重在每次试验中都有所不同，或者决策是基于复合体中具有最高水平的一个音调，那么这两种测量结果就可以协调一致。
