Auditory Processing of Stochastic FM in Relationship to Speech Perception

描述(由申请人提供)：与听力损失有关的最常见的症状是听不懂言语，特别是在不利的听力情况下。虽然其中一些困难直接与听力敏感度的丧失有关，但根据听力图中所示的检测阈值，语音处理缺陷的程度几乎总是超出预期。这项研究的主要论点是，这些扩展的语音缺陷与难以保持适当的语音信号连贯有关。当语音通过人类听觉系统的频率选择性通道进行处理时，信息可以用时间包络(E)和时间精细结构(TFS)的起伏来表示，即频率调制(FM)。这项研究的具体假设是：(1)调频的作用是维持语音的连贯性，以增强声学元素之间的连贯性，并帮助分离来自竞争来源的信号，以及(2)调频处理的缺陷在一定程度上是与听力损失和衰老相关的言语困难的原因。这些假设将在操纵刺激TFS线索的语音感知实验中得到验证，并在选择接近语音特征的信号参数的心理声学辨别测量中得到验证。包括刺激不确定性--自然语音的一个基本方面--所有提出的心理声学测量都决定了区分随机调频的低率模式的能力。建议的实验确定了区分低率FM的随机模式的能力的基础，区分了来自TFS变化的E线索的贡献。时间相关的精细结构滤波和时间中断被用来在语音清晰度测量中分离这些影响。结果将被用来评估潜在的潜在因素，当声音和电刺激相结合时，获得的语音益处。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和听力受损的人类听者辨别与语音感知相关的FM随机模式的能力。将对四个不同的受试组进行FM辨别力和言语清晰度的测量：两个听力正常的受试者被分为年轻人或老年人，两个听力损失轻到中度的受试者也是年轻人或老年人。为了评估FM歧视导致信号分离的可能性，将在安静的条件下运行，并在各种掩蔽器存在的情况下运行，这些掩蔽器代表收听者在处理语音时遇到的不同类型的干扰。根据结果，临床上可行的心理声学测量将被开发出来，以指示与听力损失和衰老相关的语音处理缺陷的程度，并有助于耳蜗性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体设备中使用的信号处理策略，这可能有助于修复语音缺陷。 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)在不利的听力环境中促进言语感知的方式，以及老年人和听力损失的听者的言语处理缺陷在多大程度上与这种调制的处理受损有关。这项工作的长期目标是开发一种临床上可行的调频处理能力的心理声学测量，以评估、诊断和帮助修复言语感知困难。

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.