Temporal weighting of interaural time and level differences

描述（由申请人提供）：本研究将考察听者如何通过不同类型的双耳线索（耳间时间差异（ITD）和耳间水平差异（ILD））组合听觉空间信息，并随着时间的推移，以更好地了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，这两种线索彼此一致，提供了关于听觉空间的冗余信息，但回声和混响会随着时间的推移扭曲这些线索，从而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敏感性如何随着声音的时间过程而变化（从而强调声音的开始），但一个关键问题仍然没有得到回答：这些变化是特定于过渡段和/或过渡段的处理，还是它们反映了线索随时间组合的方式？该研究的具体目的是通过绘制听者对ITD、ILD以及两者结合的敏感性的时间过程来解决这个问题。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），以说明过渡段和过渡段集成的神经机制随时间的动态变化。我们的目标是进一步探讨twf是否会在涉及和不涉及明显定位的任务之间发生变化（例如，辨别和指向声音）。由于许多患者群体（老年人、听力受损者、人工耳蜗使用者）在嘈杂和混响环境中听力受损，因此提高对正常听力个体处理回声和混响的机制的理解将改善(a)听觉处理缺陷的理论描述，以及(b)助听器和人工耳蜗中的信号处理算法。具体来说，绘制对过渡段和过渡段的灵敏度的时间过程可以指导数字信号处理资源的分配，以最有效地保留相关的空间信息，并减少潜在的误导性信息。

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)-and over time 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 two cues agree with one another, providing redundant information about auditory space, but echoes and reverberation distort these cues over time, thereby 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 spatial sensitivity changes over the time-course of a sound (thereby emphasizing sound onsets), but a key question remains unanswered: Are these changes specific to the processing of ITD and/or ILD, or do they reflect the manner in which the cues are combined over time? The specific aims of the proposed study address this question by mapping the time-course of listeners' sensitivity to ITD, ILD, and combinations of the two. 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. The aims further address whether TWFs vary between tasks that do and do not involve overt localization (e.g., discriminating vs. pointing to sounds). Because a number of patient populations (aging, hearing impaired, cochlear implant users) are impaired when listening in noisy and reverberant environments, an improved understanding of the mechanisms that allow normal-hearing individuals to deal with echoes and reverberation will improve (a) theoretical descriptions of auditory processing deficits, and (b) algorithms for signal processing in hearing aids and cochlear implants. Specifically, mapping the time-course of sensitivity to ITD and ILD could guide the distribution of digital signal-processing resources to most effectively preserve relevant spatial information and de-emphasize potentially misleading information.