THE IMPACT OF NOISE AND WORKING MEMORY ON ONLINE PROCESSING OF SPOKEN WORDS: EYETRACKING EVIDENCE

Abstract

Among the complaints of older adults is a difficulty in speech recognition, especially in noisy backgrounds. This difficulty can interfere with maintenance of health and quality of life and can potentially affect the rate of cognitive decline. A central research question in speech recognition in older adults is the extent to which difficulties stem from bottom-up, sensory declines that degrade the speech input, and to what extent they stem from an age-related reduction in working memory.

We used eye-tracking as an on-line measure of spoken word recognition. Listeners hear spoken instructions that relate to an object presented in the visual display, while their eye movements are recorded. For example, hearing “touch the candle,” with four objects displayed: candle, candy, dog and bicycle. As the speech signal unfolds, several alternatives are activated in response to phonemic information, i.e., CAND leads to candy and candle. In order to successfully achieve word identification, one has to inhibit phonological alternatives. Using eye-tracking, we tracked, in real-time, as the listener shifts his or her focus between candle and candy. We manipulated working memory load by using the digit pre-load task, where participants have to retain either one (low-load) or four (high-load) spoken digits for the duration of a spoken word recognition trial.

We will present three separate studies. The data show that both noise and working memory can delay speech processing. With younger adults, data suggest that the two effects may interact. Preliminary data with older adults will be discussed.