Effects of Aging and Hearing Loss During Rapid Sound Processing

描述（由申请人提供）： 这项初步研究的目的是了解记忆如何随着年龄的增长而变化，以及快速声音处理过程中工作记忆的失败是否可能导致老年退伍军人听众特别是听力损失者报告的一些言语感知困难。在快速的听觉或视觉处理过程中，已经确定了一段时间的处理干扰（和限制），称为注意瞬脱（AB）。具体地说，当受试者被要求报告嵌入在快速干扰事件流中的两个目标事件时，当第二个目标发生在第一个目标之后大约200- 400 ms的时间间隔时，报告第二个目标的能力就会减弱，就好像这个人眨眼了一样。这已被确定为工作记忆巩固的失败，并且在视觉和听觉处理过程中都是鲁棒的（Arnell，2005）。关于听觉AB如何影响年轻的正常听力听众，我们知道得很多，但对老年听众或听力损失听众的影响知之甚少。由于认知和记忆障碍是衰老的常见症状，因此在老年人中很可能存在较长时间的处理干扰。这一点很重要，因为语音是快速的，老年听众经常报告在复杂的听觉环境中有困难。此外，更有可能患有听力损失的老年听众继续报告在嘈杂环境中听力的更多问题，即使他们的助听器功能最佳。听觉系统中长时间的处理干扰的存在可以解释其中一些投诉，如果更全面地理解，可以补救。 该项目中使用的实验与已发表的听觉AB研究相似（Vachon和Tremblay，2005）。将邀请最多72名年龄为18-30岁和60-75岁的受试者参加。受试者将接受完整的听力学评估，并将其分为四组，每组15名受试者。各组将由听力正常的年轻受试者（YNH）、中度听力损伤以下的年轻受试者（YHI）、听力正常的老年受试者（ONH）和中度听力损伤以下的老年受试者（OHI）组成。将要求每名受试者收听18至26个非重叠音调，每个音调持续时间为30 ms，随后是60 ms的无声间隔。具体而言，将听到26个干扰音（452和3462 Hz之间）。T1是5000 Hz纯音，T2是由对数相关频率（600、775、1002、1295、1674 Hz）组成的复音。音调流的呈现速率将为11.1/秒（90 ms刺激起始时间）。序列可以包含（以相等的概率）a）无靶标，B）仅T1，c）仅T2或d）两种靶标。当T1出现时，它将作为7-15项出现，随机分配，在无T2试验中，后面是10个音调。当出现T2时，它可以占据随机选择的八个T1后位置（滞后1至8）中的任何一个，或者当不存在时，由干扰音替换。在每个流结束时，受试者将被要求对流是否包含T1（是/否）和T2（是/否）做出不定时的判断。在2小时的测试中将获得550个判断。这个项目是自定进度的。假设的结果是，有听力障碍或没有听力障碍的年轻听众在T1之后大约200- 400 ms时报告T2比在任何其他间隔时都更困难，与标准听觉AB一致。然而，没有听力障碍的老年听众将表现出更长时间的干扰（> 400 ms），总体表现略差，而听力障碍的老年听众将具有更长时间的处理干扰和总体更大的缺陷（较差的表现），这表明年龄的增加和听力障碍联合收割机增加了这些参与者的听觉AB。这些结果将提供一个急需的解释，说明快速处理（确切地说是语言）是如何被听力障碍、衰老以及两者的结合所削弱的。

DESCRIPTION (provided by applicant): The purpose of this pilot study is to understand how memory changes with aging and if failures of working memory during rapid sound processing may account for some of the speech perception difficulties reported by older Veteran listeners especially those with hearing loss. A period of processing interference (and limitation) has been identified during rapid auditory or visual processing, called the attentional blink (AB). Specifically, when subjects are asked to report on two targeted events embedded in a rapid stream of distractor events, the ability to report on the second target is diminished when it occurs at an interval of approximately 200-400ms following the first target, as if the person had blinked. This has been identified as a failure of working memory consolidation and is robust during both visual and auditory processing (Arnell, 2005). Much is known about how auditory AB affects young normal hearing listeners but little is known of its effect on older listeners or listeners with hearing loss. Since cognition and memory failures are common adjuncts of aging, a lengthened period of processing interference is very likely to be present among older listeners. This is important because speech is rapid and older listeners often report difficulty in complex auditory environments. Further, older listeners, who are more likely to have hearing loss, continue to report more problems hearing in noisy environments even with their hearing aids optimally functional. The presence of a prolonged period of processing interference in the auditory system could account for some of these complaints and, if more completely understood, could be remediated. Experiments used in this project are similar to published auditory AB studies (Vachon and Tremblay, 2005). Up to 72 subjects, ages 18-30 and 60-75 years will be invited to participate. Subjects will undergo a complete audiological evaluated done to assign them into one of four groups of 15 subjects each. Groups will be composed of young subjects with normal hearing (YNH), young subjects with no more than moderate hearing impairment (YHI), older subjects with normal hearing (ONH) and older subjects with no more than moderate hearing impairment (OHI). Each subject will be asked to listen to between 18 and 26 non-overlapping tones each 30ms in duration followed by a 60ms silent interval. Specifically, 26 distractor tones (between 452 and 3462 Hz) will be heard. T1 will be a 5000 Hz pure tone and T2 will be a complex tone composed of log-related frequencies (600, 775, 1002, 1295, 1674 Hz). The presentation rate of the tone stream will be 11.1/second (90ms stimulus onset asynchrony). Sequences could contain (in equal probability) a) no target, b) T1 only, c) T2 only or d) both targets. When T1 is presented it will occur as item 7-15, randomly assigned and, on no-T2 trials, is followed by 10 tones. When T2 is presented it could occupy any of eight post-T1 positions (lag 1 to 8) randomly selected or, when absent, is replaced by a distractor tone. At the end of each stream, the subject will be required to make an untimed judgment about whether the stream contained T1 (yes/no) and T2 (yes/no). 550 judgments will be obtained in 2 hours of testing. This project is self-paced. The hypothesized findings are that young listeners with or without hearing impairment will have more difficulty reporting on T2 when it follows T1 by approximately 200-400ms than at any other interval, consistent with a standard auditory AB. However, older listeners without hearing impairment will demonstrate a more prolonged period of interference (>400ms) with slightly poorer performance overall while older listeners with hearing impairment will have an even longer lasting period of processing interference and overall larger deficit (poorer performance) suggesting that increasing age and hearing impairment combine to increase the auditory AB for these participants. These results would provide a much-needed explanation of the ways in which rapid processing (precisely what speech is) is degraded by hearing impairment, aging, and a combination of the two.