Determinants of Word Recognition Speed in Older Listeners

描述（由申请人提供）： 项目摘要/摘要衰老的一个标志是难以理解快速或在嘈杂或混响条件下说出的语音。这个问题甚至在没有听力损失的老年人中也很常见。然而，它会因听力障碍而加重，并且在听力受损的人中，不能通过使用助听器来纠正。在2001年对2500万退伍军人的调查中，46%（1150万）年龄超过55岁。在55岁以上的人中，55%（630万）报告了需要助听器的听力状况。2006年，退伍军人事务部在听力损失康复方面花费了2.88亿美元。尽管许多退伍军人年龄较大，有听力损失，退伍军人事务部花费数百万美元的问题上的听力障碍，进展缓慢，以减少老龄化对听力的影响。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，包括助听器不解决时间处理损伤。 本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。目标是：确定（1）老化在多大程度上减慢了噪声中的单词识别速度;（2）受老化影响的时间处理的测量与单词识别速度相关;（3）短暂刺激的神经处理可以预测对这些相同短暂刺激的时间特性的行为敏感性。最终，我们计划使用从这项研究中获得的损伤机制和部位证据来开发听力测试和治疗方法，以满足个别退伍军人患者的听觉康复需求。 实验的目的是检查知觉和生理措施的时间处理和老年人准确，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单词识别任务中进行评估，在该任务中，识别是在噪声中测量的，作为呈现的单词部分的函数。在这个任务上的表现被认为与单词的真实的时间感知编码有关。无声间隔和包络调制的歧视将被用来获得有关时间的精细结构和包络处理的信息，因为它还不清楚这些能力将是最重要的快速识别的话。复合动作电位（CAP）和听觉脑干反应（ABR）记录在前向和同时掩蔽范式将用于确定早期神经处理的水平，有助于时间处理能力。混合效应的一般线性模型将被用来将心理物理和生理的时间处理与单词识别速度联系起来。耳蜗功能的基于耳声发射（OAE）的估计和认知处理速度的基于阅读的估计将是模型中的协变量。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，在脑干水平测量的时间精细结构处理和时间响应性将是老年人识别单词的速度的强预测因子。与听觉神经功能的关联也是预期的，而不是时间处理的更高水平的认知障碍。拟议的工作的结果将导致临床区分功能和结构阶段的时间处理可能会受到损害，这将需要显着不同的补救策略的方法。结果也将使我们能够测试目前的理论的时间处理。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，因为类似于听觉功能的年龄下降，TBI可能会导致听觉障碍，因为时间处理受损，听觉障碍可能比听力更严重。

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.