Temporal weighting of auditory spatial cues

项目摘要 这项研究将考察听众如何将不同类型的听觉空间信息组合在一起 双耳提示(耳间时间差[ITD]和耳间电平差异[ILD])、时间和跨度 频率，以便更好地理解空间听觉的动态过程 回响的环境。ITD和ILD提供了允许听众本地化的主要提示集 空间中的声音，并隔离相互竞争的声源。在理想的情况下，这些线索是一致的 频率和两种线索类型之间的关系，因此提供了有关 听觉空间。然而，回声和混响随着时间的推移扭曲了这些线索，降低了本地化程度。 和语音理解。而正常的双耳系统通过强调健壮来进行补偿 声音方面(如发音时的ITD)，正在老化、听力受损或使用 在存在回声和混响的情况下，人工耳蜗植入物仍然存在困难。 确定这些听觉处理缺陷的具体性质是困难的，因为人们对此知之甚少 关于听力正常的听者的补偿机制。过去的研究表明 研究了空间线索的影响如何在声音的时间进程中变化(因此 强调声音开头)，并跨越其频谱(通常强调空间 信息由低频率携带)，但一个关键问题仍然没有得到回答：时间进程 当存在多个频率或存在多个频率时，双耳处理是否会有所不同？相反，这样做 高频和低频的相对贡献在刺激的持续时间内会发生变化？这个 这项拟议研究的具体目的是通过描绘听众的时间进程来解决这个问题 对不同频率、带宽和一致性的声音的耳间差异的敏感性 跨频率的双耳提示。听者会以时变的方式判断声音的空间位置 ITD和/或ILD，多元回归将用来衡量这些判断的相关性 在ITD和/或ILD上。将使用回归系数来构造时态加权函数 (TWF)说明了ITD和ILD整合的神经机制随时间的动态变化以及 跨频率。平行实验将使用听觉皮质和下部的神经成像 丘脑，以及听觉外周的计算机模型，以努力确定在什么水平 这些效应发生在听觉处理的过程中。

Project Summary 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.