Ashmead D H, Davis D L, Whalen T, Odom R D
Department of Psychology, Vanderbilt University, Nashville, TN 37240.
Child Dev. 1991 Dec;62(6):1211-26.
The role of interaural time differences in infants' sound localization was investigated. One experiment on free-field sound localization corroborated previous findings that the minimum audible angle changes substantially toward the end of the first half year after birth, and 3 experiments explored interaural time discrimination in that age range. The first of these 3 experiments used an adaptive psychophysical procedure, showing that infants responded appropriately in a sound lateralization task that provides a direct measure of interaural time discrimination. The other 2 experiments improved on the psychophysical procedure by taking into account the ceiling level on performance in the task. Infants aged 16, 20, and 28 weeks had thresholds in the range of 50 to 75 microsec, with no apparent age difference. These thresholds were much lower than would be predicted from studies of free-field sound localization, indicating that sensitivity to interaural time differences is not a limiting factor for the precision of sound localization in this age range. Instead, age-related changes in free-field sound localization may reflect the need to integrate across different localization cues and to calibrate the changing values of cues due to head growth.
研究了双耳时间差异在婴儿声音定位中的作用。一项关于自由场声音定位的实验证实了先前的研究结果，即最小可听角度在出生后的前半年末会发生显著变化，并且有3项实验探讨了该年龄范围内的双耳时间辨别能力。这3项实验中的第一项采用了自适应心理物理学程序，表明婴儿在声音侧向化任务中做出了适当反应，该任务可直接测量双耳时间辨别能力。另外2项实验通过考虑任务表现的上限水平改进了心理物理学程序。16周、20周和28周大的婴儿的阈值在50到75微秒之间，没有明显的年龄差异。这些阈值远低于根据自由场声音定位研究预测的阈值，表明对双耳时间差异的敏感性不是该年龄范围内声音定位精度的限制因素。相反，自由场声音定位中与年龄相关的变化可能反映了整合不同定位线索以及校准由于头部生长而变化的线索值的需求。
