Working memory capacity modulates the effects of noise on speech recognition for non-geriatric adults
Understanding spoken communication in noisy environments is a task a majority of the world's population takes part in each day. This process is called speech perception. An individual's auditory, visual, and cognitive ability are important during speech perception in non-ideal listening conditions, and while the contributions of perceptual and cognitive abilities have been documented for younger (i.e., 18-30 years old) and older adults (i.e., 60+years old), studies have almost exclusively failed to include non-geriatric adults between 31 and 59 years old. The purpose of the current study was to identify the auditory, visual, and/or cognitive abilities, which could individually or collectively predict an individual's improvement in speech recognition performance, derived from seeing a speaker's face in a non-geriatric adult (i.e., 20-59 years old) sample. The results indicate no age-related differences in the ability to integrate audiovisual speech information. Rather, these data reveal that differences in working memory capacity (WMC) and perceptual ability modulate the noise level at which their maximum integration occurred. Non-geriatric adults with smaller working memory capacities experience maximum integration in quieter noise levels, demonstrating a reliance on perceptual abilities; however, as the environment becomes noisier their inferior WMC limits their ability to compensate and they have difficulty identifying the target speech. Alternatively, those participants with larger WMCs experience maximum integration in louder noise levels. They have a certain immunity to the effects of noise, allowing them to identify speech under poorer (i.e., louder) listening conditions. Additionally, maximum integration is experienced in more advantageous (i.e., quieter) listening conditions with increasing age, indicating the optimal noise levels for speech recognition differ with age.
Thesis (Ph.D.)-- Wichita State University, Fairmount College of Liberal Arts and Sciences, Dept. of Psychology