SPEECH UNDERSTANDING UNDER NON-OPTIMAL CONDITIONS AGING

这项拟议的研究侧重于一种特别令人不安的听觉沟通缺陷，即老年人在非最佳听力条件下理解语言的能力往往显著降低，例如在社交环境中同时进行几次对话或在混响室中。这一缺陷通常被称为随着年龄的增长而丧失的“鸡尾酒会”效应，在过去的25年里一直是越来越多的调查的焦点；然而，目前对这一缺陷的理解仍然不完整。我们之前的研究已经确定了这种缺陷的几个组成部分；那些与听力损失无关的成分与音节和分段时间范围内的空间加工和时间加工有关。这项拟议的研究将有两个具体目标：(1)调查老年人和年轻人负责听觉信号时间分析的某些特定功能，并确定当受损时，与非最佳听力条件下与年龄相关的言语理解障碍相关的那些功能；(2)在五年的时间里，确定在多大程度上可以从一般听力能力和/或特定听觉时间处理功能的恶化来预测老年人在非最佳听力条件下的言语理解能力下降的程度。该项目的意义在于，它将提供数据，可能解释为什么一些老年人能够在干扰中理解语音，而另一些人则不能。它还将阐明语音与干扰分离的分段和超分段方面，并提供关于与年龄有关的语音理解能力下降的多维概况及其与时间处理的联系的信息。通过这样做，它可能会为下一代助听器的开发提供有用的数据，这些助听器能够帮助人们理解目前可用的放大助听器无法理解的语言。这项研究将包括三个部分。第一部分将评估一大群老年人的年龄相关听力和听觉状况，包括言语加工和时间加工，并作为其他两部分的主题选择阶段。第二部分将研究在特定的时间和频谱属性上不同的非语音信号的分离。第三部分将对老年受试者群体进行为期五年的跟踪调查，并监测在干扰中实现语音理解和时间处理的功能的模式和衰退速度。

The proposed research is focused on one particularly disturbing auditory communication deficit, namely, the often markedly reduced ability of elderly individuals to understand speech under non-optimal listening conditions, such as in social settings with several simultaneously ongoing conversations or in reverberating rooms. This deficit, often referred to as the loss of the "cocktail-party" effect in aging, has been the focus of an increasing number of investigations for the last 25 years; yet, present-day understanding of the deficit is still incomplete. Our previous research has identified several components of this deficit; those that were not connected to hearing loss were related to spatial processing as well as temporal processing both in the syllabic and segmental time ranges. The proposed study will have two specific objectives: (1) investigate, in elderly and young individuals, certain specific functions responsible for temporal analysis of auditory signals, and identify those that, when impaired, are correlated with age-related deficits of speech understanding under non-optimal listening conditions, and (2) over a five-year period, determine the extent to which a decline in speech understanding under non- optimal listening conditions in elderly individuals can be predicted from the deterioration of general audiological abilities and/or specific auditory temporal processing functions. Significance of the project lies in that it will provide data that may explain why some elderly individuals are able to understand speech in interference while others are not. It will also throw light on segmental and suprasegmental aspects of the segregation of speech from interference and supply information on the multidimensional profile of the age-related decline in speech understanding and its connection to temporal processing. In doing so, it is likely to supply data useful for the development of next-generation hearing aids able to help people understand speech where presently available amplifying hearing aids do not. The study will consist of three parts. Part I will assess the age-related audiological and auditory status, including speech processing and temporal processing, in a large group of elderly individuals, and serve as a subject selection stage for the other two parts. Part II will investigate segregation of nonspeech signals differing in well specified temporal and spectral attributes. Part III will follow groups of elderly subjects over a five-year period and monitor the pattern and the rate of decline of functions that enable speech understanding and temporal processing amidst interference.