Complex sound analysis in normal and impaired ears

描述（由申请人提供）：本项目的目的是确定听力困难的性质，这些听力困难的听众听到纯音等安静声音的能力仍然相对较好。该项目的一个特别重点是老年听众，尽管听力正常，但他们很难理解背景音中的讲话。为了比较，年轻的耳蜗听力损失听众也将被检查。项目的框架是围绕3个具体目标构建的。第一个目标探讨了安静的正常阈值可能掩盖听神经水平上的永久性神经功能障碍的可能性，这种情况与噪音暴露的工作相似，表明尽管残留的神经损伤，但声学过度暴露后的敏感性可能会恢复。这一目标将导致一个更好的描述声音处理缺陷存在于面对明显良好的听力。第二个目标集中在听觉脑干反应[ABRs]引起的复杂的声音，如语音。这种类型的ABR测试的使用正在迅速增长，但对基本反应仍有许多需要了解的地方。第二个目标的直接目标是研究言语诱发ABR的年龄相关差异的特定情况，但更广泛的目标是利用本研究作为载体，更好地了解正常和耳蜗受损听觉系统中言语诱发ABR产生的多种因素。在日常听力环境中，背景声音通常在时间和频率上波动，使得目标语音本身在这些维度和耳朵之间动态变化，从而为影响语音理解的因素提供了新的视角。总之，这三个目标结合起来提供了一系列平行的研究，这些研究将极大地促进我们对复杂声音（如语音）在具有挑战性的听力环境中的处理的理解，即使对于听力相对较好的人也是如此。

DESCRIPTION (provided by applicant): The purpose of this project is to determine the nature of the hearing difficulties experienced by listeners whose ability to hear quiet sounds like pure tones is still relatively good. One particular focus of the project is on older listeners who, despte normal audiograms, find understanding speech in background sounds difficult. For comparison, younger listeners with cochlear hearing loss will also be examined. The framework of the project is structured around 3 Specific Aims. The first Aim explores the possibility that normal thresholds in quiet can belie permanent neural dysfunction at the level of the auditory nerve, a situation that parallels noise exposure work showing that recovery of sensitivity following acoustic over-exposure can occur despite residual nerve damage. This Aim will lead to a better delineation of the sound-processing deficits that exist in the face of apparently good hearing. The second Aim focuses on auditory brainstem responses [ABRs] evoked by complex sounds like speech. This type of ABR testing is rapidly growing in usage but much remains to be understood about the basic response. The immediate goal of the second Aim is to study the particular situation of age-related differences in the speech-evoked ABR, but the broader objective is to use this study as a vehicle to better understand the multiplicity of factors that contribute to the generation of the speech-evoked ABR both in the normal and cochlear-impaired auditory system. The final Aim contributes a new perspective on factors that affect speech understanding in everyday listening environments where the background sound is typically fluctuating in both time and frequency making the glimpses of target speech themselves dynamically vary across these dimensions as well as across ears. Together, these three Aims combine to provide a series of parallel studies that will significantly advance our understanding of the processing of complex sounds like speech in challenging listening environments, even for people with relatively good hearing.