Department of Cognition, Emotion, and Methods in Psychology, Faculty of Psychology, 27258University of Vienna, Wien, Austria.
Acoustics Research Institute, Austrian Academy of Sciences, Wien, Austria.
Trends Hear. 2022 Jan-Dec;26:23312165221104872. doi: 10.1177/23312165221104872.
During sound lateralization, the information provided by interaural differences in time (ITD) and level (ILD) is weighted, with ITDs and ILDs dominating for low and high frequencies, respectively. For mid frequencies, the weighting between these binaural cues can be changed via training. The present study investigated whether binaural-cue weights change gradually with increasing frequency region, whether they can be changed in various frequency regions, and whether such binaural-cue reweighting generalizes to untrained frequencies. In two experiments, a total of 39 participants lateralized 500-ms, 1/3-octave-wide noise bursts containing various ITD/ILD combinations in a virtual audio-visual environment. Binaural-cue weights were measured before and after a 2-session training in which, depending on the group, either ITDs or ILDs were visually reinforced. In experiment 1, four frequency bands (centered at 1000, 1587, 2520, and 4000 Hz) and a multiband stimulus comprising all four bands were presented during weight measurements. During training, only the 1000-, 2520-, and 4000-Hz bands were presented. In experiment 2, the weight measurements only included the two mid-frequency bands, while the training only included the 1587-Hz band. ILD weights increased gradually from low- to high-frequency bands. When ILDs were reinforced during training, they increased for the 4000- (experiment 1) and 2520-Hz band (experiment 2). When ITDs were reinforced, ITD weights increased only for the 1587-Hz band (at specific azimuths). This suggests that ILD reweighting requires high, and ITD reweighting requires low frequencies without including frequency regions providing fine-structure ITD cues. The changes in binaural-cue weights were independent of the trained bands, suggesting some generalization of binaural-cue reweighting.
在声音定位过程中，来自两耳间时间（ITD）和强度（ILD）差异的信息会被加权，其中 ITD 和 ILD 分别主导低频和高频。对于中频，通过训练可以改变这些双耳线索之间的权重。本研究旨在探讨双耳线索的权重是否随频率区域的增加而逐渐变化，是否可以在不同的频率区域内改变，以及这种双耳线索的重新加权是否可以推广到未训练的频率。在两项实验中，共 39 名参与者在一个虚拟的视听环境中对包含各种 ITD/ILD 组合的 500 毫秒、1/3 倍频程宽的噪声脉冲进行了定位。在为期 2 个会话的训练前后，测量了双耳线索的权重，根据组的不同，在训练中，要么增强 ITD，要么增强 ILD。在实验 1 中，在四个频率带（中心频率分别为 1000、1587、2520 和 4000 Hz）和一个包含所有四个带的多带刺激中进行了权重测量。在训练期间，仅呈现 1000、2520 和 4000 Hz 频段。在实验 2 中，权重测量仅包括两个中频带，而训练仅包括 1587 Hz 带。ILD 权重从低频到高频逐渐增加。当在训练中增强 ILD 时，它们会增加到 4000 Hz（实验 1）和 2520 Hz（实验 2）带。当增强 ITD 时，ITD 权重仅在 1587 Hz 带（在特定方位）增加。这表明，ILD 重新加权需要高频，而 ITD 重新加权需要不包括提供精细结构 ITD 线索的频率区域的低频。双耳线索权重的变化与训练带无关，表明双耳线索重新加权具有一定的通用性。
