Determinants of Word Recognition Speed in Older Listeners

描述(由申请人提供)： 项目摘要/摘要老龄化的一个标志是在嘈杂或有回声的情况下难以理解快速说话的语言。即使在没有听力损失的老年人中，这个问题也很常见。然而，听力受损会加重听力障碍，而在听力受损的人中，助听器的使用并不能纠正这种情况。在2001年对2500万退伍军人的调查中，46%(1150万)的人年龄在55岁以上。在55岁以上的人中，55%(630万)的人报告听力状况需要助听器。2006年，退伍军人管理局在听力损失的康复方面花费了2.88亿美元。尽管许多退伍军人年龄较大，患有听力损失，退伍军人管理局在听力障碍问题上花费了数百万美元，但在减轻老龄化对听力的影响方面进展缓慢。其中一个原因可能是，众所周知，衰老会损害时间处理，这种能力被认为会影响对快速、嘈杂或混响语音的理解。然而，目前的治疗策略，包括助听器，并没有解决时间加工障碍。这项研究的目的是更好地了解限制老年人言语理解的心理、物理和生理过程。目的是：确定(1)老化在多大程度上减慢噪声中的单词识别速度；(2)受老化影响的时间加工测量与单词识别速度相关；(3)对简短刺激的神经加工可以预测对相同短暂刺激的时间属性的行为敏感性。最终，我们计划使用这项研究产生的机制和损伤部位证据来开发听力测试和治疗，以满足个别退伍军人患者的听力康复需求。实验的目的是检查感知和生理的时间处理措施与老年人准确、自信地识别语音所需的处理时间之间的关系。受试者的表现将在时间门控的单词识别任务中进行评估，在该任务中，识别是以噪声作为呈现的单词部分的函数来衡量的。这项任务的表现被认为与对单词的实时知觉编码有关。无声间隔和包络调制的区分将被用来获得关于时间精细结构和包络处理的信息，因为尚不清楚这些能力中的哪一种对快速识别单词最重要。复合动作电位(CAPs)和听性脑干反应(ABR)记录在前向和同时掩蔽范式中，将被用来确定有助于时间加工能力的早期神经加工水平。混合效应一般线性模型将被用来将心理物理和生理时间处理与单词识别速度联系起来。在该模型中，基于耳声发射(OAE)的耳蜗功能估计和基于阅读的认知处理速度估计将是协变量。参与者将是具有一系列听力阈值的年轻人和老年人。我们假设，在脑干水平上测量的时间精细结构处理和时间反应将强烈地预测老年人识别单词的速度。与时间处理的更高水平的认知障碍相反，与听神经功能有关的关联也是可以预期的。拟议工作的结果将导致临床上区分可能损害时间加工的功能和结构阶段的方法，这将需要本质上不同的补救策略。结果还将使我们能够测试当前的时间加工理论。遭受创伤性脑损伤(TBI)的退伍军人也可能从这项工作中受益，因为与基于年龄的听觉功能下降类似，TBI可能会由于时间处理受损而导致比听力所暗示的更严重的听力损伤。

DESCRIPTION (provided by applicant): Project Summary/Abstract A hallmark of aging is difficulty understanding speech spoken rapidly or in noisy or reverberant conditions. This problem is common even among older adults who do not have hearing loss. However, it is aggravated by hearing impairment, and among those so impaired, is not corrected through hearing aid use. In a 2001 survey of 25 million Veterans, 46% (11.5 million) were over age 55. Of those over 55, 55% (6.3 million) reported a hearing condition that required a hearing aid. The VA spent $288 million on rehabilitation for hearing loss in 2006. Even though many Veterans are older and have hearing loss, and the VA spends millions of dollars on the problem of hearing impairment, progress is slow to lessen the impact of aging on hearing. One reason for this may be that aging is known to impair temporal processing, an ability thought to influence the understanding of rapid, noisy, or reverberant speech. Yet current therapeutic strategies including hearing aids do not address temporal processing impairments. The goal of this research is to better understand the psychophysical and physiological processes that limit speech understanding in the elderly. Objectives are to: Determine the extent to which (1) aging slows word recognition speed in noise; (2) those measures of temporal processing impacted by aging are associated with word recognition speed; (3) neural processing of brief stimuli can predict behavioral sensitivity to the temporal properties of those same brief stimuli. Ultimately, we plan to use mechanistic and site of lesion evidence arising from this research to develop audiometric tests and therapies to address the auditory rehabilitation needs of individual Veteran patients. Experiments are designed to examine relationships between perceptual and physiological measures of temporal processing and the processing time needed by older adults to accurately, confidently recognize speech. Subjects' performance will be evaluated for a time-gated word recognition task, in which recognition is measured in noise as a function of the portion of the word presented. Performance on this task is thought to be related to the real time perceptual encoding of words. Discrimination of silent intervals and envelope modulation will be used to obtain information about temporal fine structure and envelope processing because it is not yet clear which of these abilities would be most important for rapid recognition of words. Compound action potentials (CAPs) and auditory brainstem responses (ABRs) recorded in forward and simultaneous masking paradigms will be used to determine the levels of early neural processing that contribute to temporal processing abilities. Mixed-effects general linear modeling will be used to relate psychophysical and physiological temporal processing to word recognition speed. An otoacoustic emission (OAE) based estimate of cochlear function and a reading based estimate of cognitive processing speed will be covariates in the model. Participants will be younger and older adults with a range of hearing thresholds. We hypothesize that temporal fine structure processing and temporal responsiveness measured at the level of the brainstem will be strong predictors of the speed with which older adults recognize words. Associations with auditory nerve function are also expected, as opposed to higher level cognitive impairments of temporal processing. Results of the proposed work will lead to approaches to clinically distinguish among functional and structural stages at which temporal processing can be impaired, which would require substantially different remediation strategies. Results will also allow us to test current theories of temporal processing. Veterans that have suffered traumatic brain injury (TBI) could also potentially benefit from this work because, similar to age-based declines in auditory function, TBI may cause auditory impairment greater than hearing would suggest because of impaired temporal processing.