Spatial hearing in speech mixtures

摘要 本研究的目的是阐明空间因素在听力障碍中的作用 在一群说话者中理解一个特定说话者的言语的障碍（HI）。因为HI听众 当竞争的谈话者在空间上分开时，它的表现很差，通常认为， 空间线索是问题的根源。然而，缺乏HI听众空间缺陷的直接证据， 空间听觉和语言清晰度之间的联系也是如此。这里提出的实验将仔细 解包和表征的机制，影响听众的听力损失，在空间化的语音混合。 根据目标1提出的实验将侧重于可听度降低的影响，并确定 这一基本缺陷限制了对除了语音信息之外的空间信息的访问。刺激 在语音混合中分离出目标声音的清晰“一瞥”的处理方法将使清晰度成为可能 在没有任何明确的空间任务的情况下进行评估。对可用空间线索的控制操作 在刺激将揭示在何种程度上声学头影有助于一瞥。实验 根据这一目标，还将探讨在何种条件下获得高频率的语音是至关重要的， 将这些知识与从高频放大助听器中获得的好处联系起来。实验 目的2下提出的，旨在阐明双耳时间精细结构（TFS）在语音中的作用 混合物。工作假设是，虽然语音的幅度包络传达了主要的 高清晰度所需的信息，TFS携带声源位置的辅助线索， 分离竞争的声音。这一假设将通过比较破坏TFS对 语音清晰度的混合，其中分离是困难的相对自动。平行实验 将在相同条件下测量语音的空间位置的辨别力，以便直接 探索空间听觉和言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的损伤，这是一个仍然存在的问题， 在文学中没有解决。这项工作的一个关键方面将是仔细考虑之间的关系， “声学”TFS（使用信号处理技术提取）和“神经”TFS（如在神经系统中编码） 在语音信号的上下文中。目标3下提出的实验将研究一个相对未探索的 但在混合语音中听音的潜在关键方面：随着时间的推移， 当收听环境稳定时发生（例如，当感兴趣的讲话者保持固定在一个位置时）。一 将创建一个新的语音任务，该任务经过优化以观察不同线索的建立和可用性 将被操纵，以确定在听力正常的听众中积累的基础。表现也将 在HI听众中进行检查，以确定他们是否经历了类似的积累，结果将与 具体目标1和目标2中确定的具体缺陷。 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