Spatial hearing in speech mixtures

摘要 这项工作的目的是阐明空间因素在听者听力困难中的作用。 理解混合说话者中某一特定说话者的讲话的障碍(HI)。因为HI听众 表现不佳当相互竞争的谈话者在空间上分散时，通常认为无法利用 空间线索是问题的根源。然而，缺乏HI听者空间缺陷的直接证据， 空间听力和语言清晰度之间的明显联系也是如此。这里提出的实验将谨慎地 拆解并描述在空间化语音混合中影响听力损失的听众的机制。 在目标1下提出的实验将侧重于降低可听度的影响，并确定程度 这一基本缺陷限制了除语音信息之外对空间信息的访问。一种刺激 在语音混合中隔离目标声音的干净“一瞥”的处理方法将实现可理解性 在没有任何明确的空间任务的情况下进行评估。对可用的空间线索进行受控操作 将揭示声学头影对惊鸿一瞥的贡献程度。实验 在这一目标下，还将探讨在哪些情况下获得语音的高频是至关重要的，以及 将这些知识与高频放大助听器所获得的好处联系起来。这些实验 在目标2下提出的研究旨在阐明双耳时间精细结构在言语中的作用 混合物。工作假设是，尽管语音的幅度包络传达了主要的 高清晰度所需的信息，TFS携带声源定位的辅助提示，使 相互竞争的声音的分离。这一假设将通过比较中断TFS对 语音清晰度，适用于难以进行分离而非相对自动进行分离的混合环境。平行实验 将在相同条件下测量语音的空间位置区分度，以便直接 探索空间听力和语源分离之间的联系。在HI听众中的实验将揭示 这些听众是否表现出特别涉及双耳TFS的损害，这是一个仍然存在的问题 在文学作品中悬而未决。这项工作的一个关键方面将是仔细考虑 “声学”TFS(使用信号处理技术提取)和“神经”TFS(在听神经中编码) 在语音信号的上下文中。在目标3下提出的实验将检验一个相对未被探索的 但在混合语音中收听的潜在关键方面：随着时间的推移，可理解性的快速改善 在收听环境稳定时发生(例如，当感兴趣的说话者保持固定在一个位置时)。一个 将创建新的语音任务，并对其进行优化，以观察不同线索的建立和可用性 将被操纵，以确定听力正常的听众建立的基础。性能也将 在HI听众中进行检查，以确定他们是否经历了类似的积聚，结果将相关 对目标1和目标2中确定的具体缺陷采取个人行动。 1

Abstract The goal of this work is to clarify the role of spatial factors in the difficulty experienced by listeners with hearing impairment (HI) in understanding the speech of one particular talker in a mixture of talkers. Because HI listeners perform poorly when competing talkers are spatially separated, it is often assumed that an inability to exploit spatial cues is at the root of the problem. However, direct evidence for spatial deficits in HI listeners is lacking, as are clear links between spatial hearing and speech intelligibility. The experiments proposed here will carefully unpack and characterize the mechanisms affecting listeners with hearing loss in spatialized speech mixtures. The experiments proposed under Aim 1 will focus on the impact of reduced audibility, and determine the extent to which this basic deficit limits access to spatial information in addition to speech information. A stimulus processing approach that isolates clean “glimpses” of the target sound in speech mixtures will enable intelligibility to be assessed in the absence of any explicit spatial task. Controlled manipulation of the spatial cues available in the stimuli will reveal the extent to which acoustic head-shadow contributes to the glimpses. Experiments under this aim will also explore the conditions under which access to high frequencies in speech is critical, and relate this knowledge to the benefits obtained from high-frequency amplification hearing aids. The experiments proposed under Aim 2 are designed to clarify the role of binaural temporal fine structure (TFS) in speech mixtures. The working hypothesis is that, although the amplitude envelopes of speech convey the primary information needed for high intelligibility, TFS carries auxiliary cues for sound source location that enable segregation of competing sounds. This hypothesis will be tested by comparing the effect of disrupting TFS on speech intelligibility for mixtures in which segregation is difficult versus relatively automatic. Parallel experiments will measure discrimination of the spatial location of speech sounds under the same conditions, in order to directly explore the link between spatial hearing and speech source segregation. Experiments in HI listeners will reveal whether these listeners exhibit an impairment specifically involving binaural TFS, an issue that remains unresolved in the literature. A critical aspect of this work will be to carefully consider the relationship between “acoustic” TFS (extracted using signal processing techniques) and "neural" TFS (as coded in the auditory-nerve) in the context of speech signals. The experiments proposed under Aim 3 will examine a relatively unexplored but potentially crucial aspect of listening in speech mixtures: the rapid improvement in intelligibility over time that occurs when the listening environment is stable (e.g., when the talker of interest stays fixed at one location). A new speech task will be created that is optimized to observe the build-up, and the availability of different cues will be manipulated to determine the basis of the build-up in listeners with normal hearing. Performance will also be examined in HI listeners to determine whether they experience a similar build-up, and results will be related on an individual basis to the specific deficits identified in Aims 1 and 2. 1