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[ITD]和耳间电平差[ILD]）中，随着时间的推移和频率的变化，联合收割机听觉空间信息，以便更好地理解混响环境中空间听觉的动态过程。ITD和ILD提供了一组主要的线索，使听众能够在空间中定位声音并隔离竞争声源。在理想情况下，线索同意跨频率和两种线索类型之间，因此提供了关于听觉空间的冗余信息。然而，回声和混响会随着时间的推移扭曲这些线索，降低定位和语音理解。虽然正常的双耳系统通过强调声音的鲁棒方面（例如开始时的ITD）进行补偿，但老化，听力受损或使用人工耳蜗的听众在回声和混响存在的情况下仍然会遇到困难。确定这些听觉处理缺陷的具体性质是困难的，因为对正常听力的听众中起作用的补偿机制知之甚少。过去的研究已经调查了空间线索的影响如何在声音的时间过程中变化（从而强调声音开始），并在其频谱上（通常强调低频携带的空间信息），但一个关键问题仍然没有答案：双耳处理的时间过程是否在频率上变化或当存在多个频率时？相反，高频率和低频率的相对贡献是否会在刺激持续时间内发生变化？拟议的研究的具体目标解决这个问题，映射的时间过程中的听众的敏感性，耳间差异的声音不同的频率，带宽和协议的双耳线索跨频率。听众将判断声音的空间位置与时变ITD和/或ILD，和多元回归将被用来衡量这些判断ITD和/或ILD的依赖性。回归系数将用于构建时间加权函数（TWF），其说明了ITD和ILD随时间和频率整合的神经机制的动态。平行实验将使用听觉皮层和下丘的神经成像技术，以及听觉外围的计算机模型，沿着，以努力确定这些影响发生在听觉处理的哪个水平。 公共卫生相关性：由于许多患者人群（老年人、听力受损者、人工耳蜗植入者）在嘈杂和混响环境中听力受损，因此，对听力正常者处理回声和混响的机制的更好理解将改善（a）听觉处理缺陷的理论描述，以及（B）助听器和人工耳蜗植入物中信号处理的算法。具体而言，跨频率映射对ITD和ILD的敏感性的时间过程可以指导数字信号处理资源的分布，以最有效地保留相关的空间信息并淡化潜在的误导信息。

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]), 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. Parallel experiments will use neuroimaging of the auditory cortex and inferior colliculus, along with computer models of the auditory periphery, in an effort to identify at what level of auditory processing these effects take place. PUBLIC HEALTH RELEVANCE: 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 across frequency could guide the distribution of digital signal-processing resources to most effectively preserve relevant spatial information and de-emphasize potentially misleading information.