Temporal weighting of interaural time and level differences

描述（由申请人提供）：本提案是对NOT-OD-09-058号通知的回应：NIH宣布为竞争性修订申请提供恢复法案资金。拟议的研究将研究人类听觉皮层（AC）如何随着时间的推移对不同类型的双耳信息（特别是来自耳间时间差（ITD）和耳间水平差（ILD）的信息）的组合做出反应。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。在理想的情况下，这两个线索彼此一致，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而扭曲ITD和ILD值，从而降低定位和语音理解。这些影响在衰老、听力障碍和耳蜗植入物使用中尤其严重，可能反映了正常代偿机制的功能障碍，这些机制强调声音的各个方面（如开始时的ITD），这些方面对回声的影响更强大。这一领域的先前研究已经调查了空间灵敏度如何随声音的时间过程而变化，并且一些研究表明AC保持听觉空间线索的多种表示，以对混响环境的特征敏感的方式将这些线索中的信息组合起来。拟议的修订使用功能性磁共振成像（fMRI）来测量AC响应对刺激双耳配置变化的敏感性。的具体目标是解决AC中的活动是否对双耳信息的时间结构表现出敏感性（例如，AC是否对声音开始中包含的线索的响应超过声音的后续部分？）反过来，AC活动是否反映了刺激的感知或物理配置（当两者不同时）。这些目标进一步解决了各种候选空间线索（发作时和之后的ITD和ILD）是否共同或独立地影响AC响应的形成，以及这些影响是否在人类AC的功能不同的子区域中变化。 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。此外，映射听觉皮层区域对双耳参数变化的敏感性将提高我们目前对大脑如何处理声音以及听觉皮层如何组织的理解，在正常和紊乱人群中。

DESCRIPTION (provided by applicant): This proposal is in response to Notice Number NOT-OD-09-058: NIH Announces the Availability of Recovery Act Funds for Competitive Revision Applications. The proposed research will examine how the human auditory cortex (AC) responds to combinations of different types of binaural information (specifically, information from interaural time differences, or ITD, and interaural level differences, or ILD) over time. 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. Echoes and reverberation, however, distort ITD and ILD values over time, degrading localization and speech understanding. These effects are especially severe in aging, hearing impairment, and cochlear-implant use, possibly reflecting dysfunction in normal compensatory mechanisms that emphasize aspects of sound (such as ITD at onset) that are more robust to effects of echoes. Previous research in this area has investigated how spatial sensitivity varies over the time-course of a sound, and some studies have suggested that the AC maintains multiple representations of auditory spatial cues, combining information across these cues in a manner that is sensitive to characteristics of the reverberant environment. The proposed revision uses functional magnetic resonance imaging (fMRI) to measure the sensitivity of AC responses to changes in the binaural configuration of a stimulus. The specific aims of address whether activity in the AC exhibits sensitivity to the temporal structure of binaural information (for example, does the AC respond to cues contained in the onset of a sound more than later parts of a sound?) and in turn whether AC activity reflects the perception or the physical configuration of a stimulus (when the two differ). The aims further address whether various candidate spatial cues (ITD and ILD at onset and thereafter) contribute together or independently in shaping AC responses, and whether those contributions vary across functionally distinct sub-regions of human AC. 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. Furthermore, mapping the sensitivity of auditory cortical regions to variation in binaural parameters will improve our current understanding of how the brain processes sound, and how auditory cortex is organized, in normal and disordered populations.