Zera J, Green D M
Department of Psychology, University of Florida, Gainesville 32611.
J Acoust Soc Am. 1993 Feb;93(2):1038-52. doi: 10.1121/1.405552.
The ability of listeners to detect asynchrony in either the temporal onset or offset of components in multicomponent complexes was measured. The listener discriminated a standard complex, one in which all components were synchronous, from an asynchronous complex. In the initial experiments, asynchrony was created by starting (onset experiments) or ending (offset experiments) the harmonics at times drawn from a Gaussian distribution. In later experiments, asynchrony was created by starting or terminating only certain components before or after the other components in the complex. One complex consisted of 20 harmonic components with a fundamental of 200 Hz. Another multicomponent complex used components spaced at equal intervals in logarithmic frequency (200 to 4000 Hz). The parameters investigated were rise or decay time of components, duration of a complex, and frequency position of displaced components. The obtained thresholds were different for onset and offset asynchrony. For onset asynchrony in harmonic complexes, the thresholds were a nonmonotonic function of rise time with a minimum of 0.2 ms obtained for a rise time of 1 ms. For offset asynchrony, thresholds were generally monotonic with increases in decay time and ranged from 0.45-1.3 ms. Experiments with a much shorter signal duration demonstrated that forward and backward masking played little role in the observed differences in thresholds. Onset thresholds for harmonic stimuli measured as a function of the frequency region of the asynchronous component(s) showed a minimum of 0.2 ms at about 2000 Hz. The thresholds for offset were about ten times larger. For logarithmic complexes, in some conditions, thresholds were larger by nearly two orders of magnitude. Experiments in which the listeners discriminated changes either in the onset or offset envelope of the wideband stimulus suggest that detection of temporal asynchrony depends on comparison between frequency channels rather than on differences in the temporal onset or offset of the overall energy of the sounds.
测量了听众检测多成分复合体中成分在时间起始或结束时异步性的能力。听众将一个标准复合体（其中所有成分都是同步的）与一个异步复合体区分开来。在最初的实验中，异步性是通过从高斯分布中抽取时间来启动（起始实验）或结束（结束实验）谐波而产生的。在后来的实验中，异步性是通过在复合体中的其他成分之前或之后仅启动或终止某些成分而产生的。一个复合体由20个谐波成分组成，基频为200赫兹。另一个多成分复合体使用在对数频率（200至4000赫兹）上等间隔分布的成分。所研究的参数包括成分的上升或衰减时间、复合体的持续时间以及移位成分的频率位置。对于起始和结束异步性，获得的阈值是不同的。对于谐波复合体中的起始异步性，阈值是上升时间的非单调函数，上升时间为1毫秒时获得的最小值为0.2毫秒。对于结束异步性，阈值通常随着衰减时间的增加而单调变化，范围为0.45 - 1.3毫秒。信号持续时间短得多的实验表明，前向和后向掩蔽在观察到的阈值差异中起的作用很小。作为异步成分频率区域的函数测量的谐波刺激的起始阈值在约2000赫兹处显示最小值为0.2毫秒。结束阈值大约大十倍。对于对数复合体，在某些条件下，阈值大近两个数量级。听众辨别宽带刺激的起始或结束包络变化的实验表明，时间异步性的检测取决于频率通道之间的比较，而不是声音总能量在时间起始或结束上的差异。
