Department of Experimental Psychology, University of Cambridge, Cambridge, United Kingdom.
Department of Speech, Language, and Hearing Sciences, Purdue University, West Lafayette, Indiana 47907, USA.
J Acoust Soc Am. 2018 Mar;143(3):1287. doi: 10.1121/1.5025845.
Sensitivity to interaural time differences (ITDs) in envelope and temporal fine structure (TFS) of amplitude-modulated (AM) tones was assessed for young and older subjects, all with clinically normal hearing at the carrier frequencies of 250 and 500 Hz. Some subjects had hearing loss at higher frequencies. In experiment 1, thresholds for detecting changes in ITD were measured when the ITD was present in the TFS alone (ITD), the envelope alone (ITD), or both (ITD). Thresholds tended to be higher for the older than for the young subjects. ITD thresholds were much higher than ITD thresholds, while ITD thresholds were similar to ITD thresholds. ITD thresholds were lower than ITD thresholds obtained with an unmodulated pure tone, indicating that uninformative AM can improve ITD discrimination. In experiment 2, equally detectable values of ITD and ITD were combined so as to give consistent or inconsistent lateralization. There were large individual differences, but several subjects gave scores that were much higher than would be expected from the optimal combination of independent sources of information, even for the inconsistent condition. It is suggested that ITD and ITD cues are processed partly independently, but that both cues influence lateralization judgments, even when one cue is uninformative.
对年轻和老年受试者在包络和调制幅度（AM）音调的时间精细结构（TFS）中的耳间时间差（ITD）的敏感性进行了评估，所有受试者的临床听力均在载波频率为 250 和 500Hz 时正常。一些受试者在更高频率处存在听力损失。在实验 1 中，当 TFS 中存在 ITD（ITD）、包络中存在 ITD（ITD）或两者都存在 ITD 时，测量了检测 ITD 变化的阈值。对于老年受试者而言，阈值往往高于年轻受试者。ITD 阈值比 ITD 阈值高得多，而 ITD 阈值与 ITD 阈值相似。ITD 阈值比使用未调制纯音获得的 ITD 阈值低，表明无信息 AM 可以改善 ITD 辨别。在实验 2 中，组合了等可检测的 ITD 和 ITD 值，以便给出一致或不一致的侧向化。存在较大的个体差异，但有几个受试者的得分远高于独立信息源的最佳组合预期值，即使在不一致的情况下也是如此。建议 ITD 和 ITD 线索部分独立处理，但两者都影响侧向化判断，即使一个线索无信息。
