Effects of Aging and Hearing Loss During Rapid Sound Processing

描述(由申请人提供)： 这项先导性研究的目的是了解记忆是如何随着年龄的增长而变化的，以及快速声音处理过程中工作记忆的失败可能是老年听众，特别是听力受损的人报告的一些言语感知困难的原因。在快速听觉或视觉加工过程中，已经发现了一段时间的加工干扰(和限制)，称为注意眨眼(AB)。具体地说，当受试者被要求报告嵌入快速分心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200-400ms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。这被认为是工作记忆巩固的失败，在视觉和听觉加工过程中都是健壮的(Arnell，2005)。关于听觉AB如何影响听力正常的年轻听者，我们知道的很多，但对年长的听者或听力损失的听者的影响却知之甚少。由于认知和记忆障碍是衰老的常见附属物，因此较年长的听者很可能存在较长时间的加工干扰。这一点很重要，因为说话速度很快，而年长的听众经常报告在复杂的听觉环境中有困难。此外，年长的听者更有可能患有听力损失，即使他们的助听器功能最佳，他们在嘈杂的环境中也会继续报告更多的听力问题。听觉系统中存在较长时间的加工干扰可能是这些投诉中的一些原因，如果更全面地了解，就可以补救。该项目中使用的实验类似于已发表的听觉AB研究(Vachon和Tremblay，2005)。最多将邀请72名年龄在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，将他们分成四组，每组15名受试者。分组将包括听力正常的年轻人(YNH)、听力损伤不超过中度的年轻人(YHI)、听力正常的老年人(ONH)和听力障碍不超过中度的老年人(OHI)。每个受试者将被要求听18到26个不重叠的音调，每个音调持续30毫秒，然后是60毫秒的静音间隔。具体来说，将听到26个干扰音(在452至3462赫兹之间)。T1将是5000赫兹纯音，T2将是由对数相关频率(600、775、1002、1295、1674赫兹)组成的复音。音频流的呈现速率将为11.1/秒(90ms刺激开始异步)。序列可以包含(以相等的概率)a)没有目标、b)仅包含t1、c)仅包含t2或d)两个目标。当T1出现时，它将作为第7-15项出现，随机分配，在无T2试验中，后面跟随10个音调。当T2出现时，它可以占据随机选择的8个T1后位置(滞后1到8)中的任何一个，或者当不存在时，用分心音调来代替。在每个流的末尾，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。550个判决将在2小时的测试中获得。这个项目是自定进度的。假设的发现是，无论有没有听力障碍的年轻听者，当T2在T1之后大约200-400ms时，报告T2将比任何其他间隔更困难，这与标准的听觉AB一致。然而，没有听力障碍的老年听众将表现出更长的干扰时间(&gt；400ms)，总体表现略差，而患有听力障碍的老年听众处理干扰的时间更长，总体缺陷更大(表现更差)，这表明年龄和听力障碍的增加共同增加了这些参与者的听觉AB。这些结果将为快速处理(准确地说是语音)是如何因听力受损、衰老以及两者的组合而退化的方式提供亟需的解释。 公共卫生相关性： 听力损失是最常见的健康问题之一，60岁以上的美国人中有1/3受到影响，85岁以上的人中有1/2受到影响。2009年，退伍军人管理局以超过1.955亿美元的价格发放了近47.6万套助听器，减少了听力障碍对社会和情感孤立的影响。认知和记忆过程对听力的贡献被普遍认为是充分言语交流的关键，但这些过程并没有被很好地理解。快速处理连续声音的能力在所有听众中都会出现认知限制，但对有听力障碍和没有听力障碍的老年退伍军人可能会有更大的影响。这一点很重要，因为语音是快速和连续的。如果能够更完整地描述这种处理限制，它最终可以指导现实世界相关测试和治疗的发展，从而扩大助听器对所有退伍军人的好处。

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. PUBLIC HEALTH RELEVANCE: Hearing loss is one of the most common health concerns affecting 1 in 3 Americans over 60 years of age rising to 1 in 2 for those over 85 years old. The VA issued nearly 476,000 hearing aids in 2009 at a cost of over $195.5M, reducing the impact that hearing impairment adds to social and emotional isolation. Contributions to hearing abilities provided by cognitive and memory processes are universally recognized as essential to adequate speech communication, but these processes are not well understood. Cognitive limitations in the ability to rapidly process sequential sounds occur with all listeners but may have more impact on older Veterans with and without hearing impairment. This is important since speech is rapid and sequential. If this processing limitation can be characterized more completely, it could eventually guide the development of real- world relevant tests and therapies, thereby extending the benefits of hearing aids for all Veterans.