Effects of age, hearing loss, and linguistic complexity on listening effort as measured by working memory span

Abstract

Listeners, especially older or hard-of-hearing individuals, report that understanding conversation in noisy situations is effortful. Individual differences may be due to auditory and/or cognitive processing abilities. It is assumed that auditory processing depends on the individual’s degree and type of hearing loss, while cognitive processing depends on the individual’s working memory (WM) capacity. Many researchers have measured reading WM span to minimize the effects of hearing loss; however, variations due to hearing loss may be important in assessing processing demands (listening effort) during speech-in-noise understanding. The effects of the acoustical properties of the signal and masker on listening effort have been studied, but less is known about the effects of the linguistic complexity of the materials. We predicted that demands on WM and the correlation between WM span measures and speech-in-noise performance would increase with increasing linguistic complexity, with speech-in-noise performance correlating more strongly with auditory than with visual measures of WM span. To test these hypotheses, we administered speech tests varying in linguistic complexity and measures of both reading and listening WM span. Participants were a group of younger listeners with normal hearing and a group of older listeners with bilateral sensorineural hearing loss.