Hill N I, Bailey P J
Department of Psychology, University of York, United Kingdom.
J Acoust Soc Am. 1998 Aug;104(2 Pt 1):1008-12. doi: 10.1121/1.423320.
Listeners' thresholds for discriminating changes in the relative intensities of two octave-spaced pure tones were measured in three conditions using a 2AFC procedure. In the baseline condition the tone pair was presented alone, while in the two interference conditions the tone pair was accompanied by four additional tones, with the frequency separation between adjacent components of the resultant six-component complex being one octave. In the interference conditions the flanking components were either gated synchronously with the target pair, or began 200 ms ahead. The level of the flanking components relative to the target was randomized on each presentation. The overall stimulus level was also randomized on each presentation to reduce the effectiveness of within-channel comparisons. Threshold elevations in the synchronous condition relative to the baseline ranged from approximately 5 to 17 decibels. By contrast, in the asynchronous condition only one listener showed significant (although substantially reduced) interference. The results complement previous observations that across-channel intensity comparisons are poorer between components that begin or end at different times, and are qualitatively consistent with the hypothesis that temporal misalignment promotes the perceptual segregation of simultaneous frequency components.
使用二选一的强迫选择程序，在三种条件下测量了听众辨别两个相隔一个八度的纯音相对强度变化的阈值。在基线条件下，仅呈现音对，而在两种干扰条件下，音对伴随着另外四个音调，合成的六分量复合体相邻成分之间的频率间隔为一个八度。在干扰条件下，侧翼成分要么与目标音对同步选通，要么提前200毫秒开始。每次呈现时，侧翼成分相对于目标的电平是随机的。每次呈现时，整体刺激电平也随机化，以降低通道内比较的有效性。同步条件下相对于基线的阈值升高范围约为5至17分贝。相比之下，在异步条件下，只有一名听众表现出显著的（尽管大幅降低的）干扰。这些结果补充了先前的观察结果，即开始或结束时间不同的成分之间跨通道强度比较较差，并且在定性上与时间错位促进同时存在的频率成分的感知分离这一假设一致。
