Auditory Processing of Stochastic FM in Relationship to Speech Perception

描述（由申请人提供）：与听力损失相关的最常见抱怨是理解言语，特别是在不利的听力情况下。虽然其中一些困难与听力敏感性的丧失直接相关，但语音处理缺陷的程度几乎总是超出了基于听音图中所表示的检测阈值的预期。本研究的主要论点是，这些扩展的言语缺陷与维持适当的言语信号连贯性的困难有关。当语音通过人类听觉系统的频率选择通道进行处理时，信息可以用时间包络(E)和时间精细结构（TFS）的波动表示为调频（FM）。该研究提出的具体假设是，对于语音，(1)调频的作用与维持语音连贯性有关，以增强声学元素之间的流，并帮助从竞争源中分离信号；(2)调频处理缺陷部分直接导致了与听力损失和衰老相关的语言困难。这些假设将在语音感知操纵刺激TFS线索的实验和选择近似语音特征的信号参数的心理声学辨别措施中得到验证。结合刺激的不确定性——自然语言的一个基本方面——所有提出的心理声学测量都决定了在随机调频的低频率模式中区分的能力。提出的实验确定了区分低频率FM随机模式的能力基础，区分来自TFS变化的E线索的贡献。在语音可理解度测量中，采用时间相关的精细结构滤波和时间中断来分离这些影响。结果将用于评估声学和电刺激相结合所获得的语音益处的潜在因素。使用由初始工作结果确定的条件参数值，拟议的研究将测量老年人和听力受损的人类听众区分与语音感知相关的FM随机模式的能力。FM辨别和言语清晰度将在四个不同的受试者组中进行测量：两组听力正常，分为年轻人和老年人，两组听力轻度至中度损失，分为年轻人和老年人。为了评估调频辨别对信号隔离的潜在影响，实验将在安静的环境下进行，并在各种掩蔽器的存在下进行，这些掩蔽器代表听者在演讲时面临的不同类型的干扰。基于结果，临床可行的心理声学测量将被开发出来，以表明与听力损失和衰老相关的语言处理缺陷的程度，并有助于耳蜗听力损失的早期诊断。从临床人群中获得的结果应该建议在假肢装置中使用信号处理策略，这可能有助于纠正语言缺陷。

DESCRIPTION (provided by applicant): The most common complaint associated with hearing loss is understanding speech, especially in adverse listening situations. While some of this difficulty directly relates to loss in hearing sensitivity, the extent of the speech-processing deficits almost always exceeds expectations based on detection thresholds as represented in the audiogram. The primary thesis of the proposed research is that these extended speech deficits relate to difficulty maintaining proper speech-signal coherence. When speech is processed through the frequency- selective channels of the human auditory system, the information can be represented in terms of fluctuation of the temporal envelope (E) and temporal fine structure (TFS) as frequency modulation (FM). The specific hypotheses of the proposed study are that for speech, (1) the role of FM relates to maintaining speech coherence to enhance streaming across acoustic elements and aid segregation of the signal from competing sources, and (2) that deficits in FM processing are in part directly responsible for speech difficulties associated with hearing loss and aging. These hypotheses will be tested in experiments of speech perception manipulating stimulus TFS cues and in psychoacoustic discrimination measures with signal parameters chosen to approximate speech characteristics. Incorporating stimulus uncertainty-a fundamental aspect of natural speech-all proposed psychoacoustic measures determine ability to discriminate among low-rate patterns of stochastic FM. Proposed experiments determine the basis of the ability to discriminate among stochastic patterns of low-rate FM, distinguishing contribution of E cues derived from TFS variation. Time-dependent fine-structure filtering and temporal interruption are used to separate these effects in measures of speech intelligibility. Results will be used to evaluate potential factors underlying the speech benefit obtained when combining acoustic and electrical stimulation. Using condition parameter values determined by results from initial work, proposed research will measure the ability of both elderly and hearing-impaired human listeners to discriminate stochastic patterns of FM relevant to speech perception. FM discrimination and speech intelligibility will be measured for four different subject groups: two with normal hearing grouped as either young or elderly, and two with a mild-to-moderate hearing loss, again either young or elderly. To evaluate the potential for FM discrimination contributing to signal segregation, conditions will be run in quiet and in the presence of a variety of maskers that represent different types of interference that listeners confront when attending to speech. Based on results, clinically feasible psychoacoustic measures will be developed to indicate the extent of the speech-processing deficits associated with hearing loss and aging, and aid in the early diagnosis of cochlear hearing loss. Results obtained from clinical populations should suggest signal-processing strategies for use in prosthetic devices that may help remediate speech deficits. PUBLIC HEALTH RELEVANCE: The project will provide a basis for understanding the manner by which low-rate frequency modulation (FM) contributes to speech perception in adverse listening environments, and the extent to which the speech-processing deficits of the elderly and listeners with hearing loss relate to impaired processing of this modulation. The long-term goal of this work is to develop a clinically feasible psychoacoustic measure of FM processing ability to assess, diagnosis, and aid in the remediation of difficulties with speech perception.