Date of Award

2011

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Communication Sciences and Disorders

Advisor(s)

Karen A. Doherty

Keywords

Aging, Hearing Loss, Listening Effort, Speech Recognition

Subject Categories

Speech Pathology and Audiology

Abstract

It is well established that older listeners have more difficulty understanding speech in background noise than younger listeners (e.g. Dubno et. al., 1984). Some have attributed this increased difficulty to peripheral hearing loss, while others suggest that older listeners may perceive listening in noise as difficult and effortful because it requires them to exert more cognitive resources (Desjardins et. al., 2009). The purpose of the present study was to directly evaluate the relationship between cognitive function, listening effort and speech recognition for a group of younger and older normal hearing adults, and a group of older adults with hearing impairment, in various types of background noise.

A dual-task paradigm was used to objectively evaluate listening effort. The primary task required participants to repeat sentences presented in three different background noise masker conditions (e.g. Two-Talker (TT), Six-Talker (SIX), Speech-Shaped Noise (SSN)). The secondary task was a digital visual pursuit rotor tracking test (DPRT), for which participants were instructed to use a computer mouse to track a moving target around an ellipse that was displayed on a computer screen. Each task was presented separately and concurrently at a fixed speech recognition performance level of 76% correct. In addition, participants' subjectively rated how easy it was to listen to the sentences in each masker condition on a scale from 0 (e.g. very difficult) to 100 (e.g. very easy). Last, participants completed a battery of cognitive tests which measured working memory (Reading Span test), processing speed (DSST) and selective attention (Stroop test) ability.

Results revealed that participants' working memory and processing speed ability were significantly related to their speech recognition performance in noise in all three background noise masker conditions. Both groups of older participants expended significantly more listening effort than younger participants in the SSN and TT masker conditions. For each group of participants, there were no significant differences in listening effort measured across the masker conditions, with the exception of the younger participants who expended more effort listening in the SIX masker condition compared to the SSN condition. All participants' listening effort expended on the TT and SSN masker conditions was significantly correlated with their working memory and processing speed performance. Participants' subjective ratings of listening effort did not correlate with their objective measures of listening effort on any of the listening conditions. Findings from the present study indicate that older adults, independent of peripheral hearing loss, require more cognitive resources than younger adults to understand speech in background noise.

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Open Access

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