Temporal weighting of interaural time and level differences

描述(申请人提供)：这项研究将考察听者如何结合不同类型的双耳线索的听觉空间信息-耳间时间差(ITD)和耳间电平差(ILD)-以及随着时间的推移，以便更好地理解混响环境中潜在的空间听力的动态过程。ITD和ILD提供了一套主要的线索，允许听众在空间中定位声音并隔离竞争的声源。在理想情况下，这两个线索彼此一致，提供了关于听觉空间的多余信息，但回声和混响随着时间的推移扭曲了这些线索，从而降低了本地化和语音理解能力。虽然正常的双耳系统通过强调声音的强健方面(如开始时的ITD)来进行补偿，但年龄较大、听力受损或使用人工耳蜗的听者在存在回声和混响时仍会遇到困难。确定这些听觉处理缺陷的具体性质是困难的，因为人们对听力正常的听者的补偿机制知之甚少。过去的研究已经研究了空间敏感度如何随着声音的时间进程而变化(从而强调了声音开头)，但一个关键问题仍然没有得到回答：这些变化是ITD和/或ILD加工所特有的，还是反映了线索随着时间的推移而组合的方式？这项研究的具体目的是通过描绘听者对ITD、ILD以及两者的组合的敏感度的时间进程来解决这个问题。听者会用时变的ITD和/或ILD来判断声音的空间位置，而多元回归将被用来衡量这些判断对ITD和/或ILD的依赖性。回归系数将被用来构建时间加权函数(TWF)，该函数说明ITD和ILD整合的神经机制随时间的动态变化。这些目标进一步解决了TWF是否在涉及和不涉及公开本地化的任务之间存在差异(例如，辨别和指向声音)。由于许多患者群体(老龄化、听力受损、人工耳蜗者)在嘈杂和混响的环境中听力受损，因此对听力正常的个体处理回声和混响的机制的更好理解将改进(A)听觉处理缺陷的理论描述，以及(B)助听器和人工耳蜗术中信号处理的算法。具体地说，将敏感性的时间进程映射到ITD和ILD可以指导数字信号处理资源的分布，以最有效地保存相关的空间信息，并不强调潜在的误导性信息。

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.