Temporal weighting of auditory spatial cues

描述（由申请人提供）：本研究将研究听者如何在不同类型的双耳线索（耳间时间差异[ITD]和耳间水平差异[ILD]）、时间和频率上组合听觉空间信息，以便更好地理解混响环境中空间听力的动态过程。ITD和ILD提供了一组主要的线索，使听者能够在空间中定位声音并分离竞争的声源。在理想情况下，线索在频率和两种线索类型之间是一致的，因此提供了关于听觉空间的冗余信息。然而，随着时间的推移，回声和混响会扭曲这些线索，降低定位和语言理解。正常双耳系统通过强调声音的健壮方面（如开始时的过渡段）进行补偿，而老年人、听力受损者或使用人工耳蜗的听者在回声和混响的存在下仍然感到困难。确定这些听觉处理缺陷的具体性质是困难的，因为对正常听力听众的补偿机制所知甚少。过去的研究已经调查了空间线索的影响是如何随着声音的时间过程（因此强调声音的开始）和频谱（通常强调低频携带的空间信息）而变化的，但一个关键问题仍然没有得到回答：双耳处理的时间过程是随着频率的变化还是当多个频率存在时？相反，高频和低频的相对贡献是否会随着刺激的持续时间而变化？该研究的具体目的是通过绘制听者对不同频率、带宽的声音的耳际差异的敏感性的时间过程，以及跨频率双耳线索的一致性来解决这个问题。听者会根据时变的过渡段和/或过渡段来判断声音的空间位置，并使用多元回归来衡量这些判断对过渡段和/或过渡段的依赖性。回归系数将用于构建时间加权函数（twf），以说明过渡段和ILD随时间和频率整合的神经机制的动态。

DESCRIPTION (provided by applicant): This research will examine how listeners combine auditory spatial information across different types of binaural cues (interaural time differences [ITD] and interaural level differences [ILD]), over time, and across frequency in order to better understand the dynamic processes underlying spatial hearing in reverberant environments. ITD and ILD provide the major set of cues that allow listeners to localize sounds in space and to segregate competing sound sources. In ideal situations, the cues agree across frequency and between the two cue types, and therefore provide redundant information about auditory space. Echoes and reverberation, however, distort these cues over time, degrading localization and speech understanding. Whereas the normal binaural system compensates by emphasizing robust aspects of the sound (such as ITD at onset), listeners who are aging, hearing-impaired, or using cochlear implants continue to experience difficulty in the presence of echoes and reverberation. Identifying the specific nature of these auditory processing deficits is difficult because so little is known about the compensatory mechanisms at work in normal-hearing listeners. Past research has investigated how the influence of spatial cues varies over the time-course of a sound (thereby emphasizing sound onsets), and across its frequency spectrum (typically emphasizing spatial information carried by low frequencies) but a key question remains unanswered: does the time-course of binaural processing vary across frequency or when multiple frequencies are present? Conversely, do the relative contributions of high- and low-frequencies change over the duration of a stimulus? The specific aims of the proposed study address this question by mapping the time-course of listeners' sensitivity to interaural differences for sounds varying in frequency, bandwidth, and the agreement of binaural cues across frequency. Listeners will judge the spatial positions of sounds with time-varying ITD and/or ILD, and multiple regression will be used to measure the dependence of those judgments on ITD and/or ILD. Regression coefficients will be used to construct temporal weighting functions (TWFs) that illustrate the dynamics of neural mechanisms for integration of ITD and ILD over time and across frequency.