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投诉是理解言语，特别是在不利的听力情况下。虽然这种困难中的一些直接与听力灵敏度的损失有关，但语音处理缺陷的程度几乎总是超过基于听力图中所表示的检测阈值的预期。所提出的研究的主要论点是，这些扩展的语音缺陷涉及到难以保持适当的语音信号的连贯性。当语音通过人类听觉系统的频率选择性通道进行处理时，信息可以根据时间包络（E）的波动和时间精细结构（TFS）来表示为频率调制（FM）。拟议研究的具体假设是，对于语音，（1）FM的作用与维持语音连贯性有关，以增强声学元素之间的流传输并帮助分离来自竞争源的信号，以及（2）FM处理的缺陷部分直接导致与听力损失和衰老相关的言语困难。这些假设将在实验中的语音感知操纵刺激TFS线索和心理声学的歧视措施与信号参数选择近似的语音特征进行测试。消除刺激的不确定性-一个基本方面的自然语音-所有提出的心理声学措施确定的能力，以区分低速率模式的随机调频。建议的实验确定的基础上的能力，以区分随机模式的低速率FM，区分贡献的E线索来自TFS的变化。时间相关的精细结构滤波和时间中断被用来分离这些影响的语音清晰度的措施。结果将用于评价声电刺激结合时获得的言语益处的潜在因素。使用条件参数值确定的结果从最初的工作，拟议的研究将衡量老年人和听力受损的人类听众的能力，以区分随机模式的FM相关的语音感知。将测量四个不同受试者组的FM辨别力和语言清晰度：两个听力正常的受试者组分为年轻人或老年人，两个听力轻度至中度损失的受试者组也分为年轻人或老年人。为了评估FM歧视对信号隔离的潜在影响，将在安静和存在各种掩蔽物的情况下运行条件，这些掩蔽物代表听众在听演讲时面临的不同类型的干扰。根据结果，将开发临床可行的心理声学措施，以指示与听力损失和衰老相关的语音处理缺陷的程度，并帮助早期诊断耳蜗听力损失。从临床人群中获得的结果应建议用于修复设备，可能有助于修复语音缺陷的信号处理策略。 公共卫生相关性：该项目将提供一个基础，以了解低速率调频（FM）的方式有助于在不利的听力环境中的语音感知，以及老年人和听力损失的听众的语音处理缺陷与这种调制的受损处理的程度。这项工作的长期目标是开发一种临床上可行的心理声学措施FM处理能力，以评估，诊断，并帮助补救的困难与语音感知。

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.