The purpose of the present study was to evaluate the relationship between cognitive function, listening effort, and speech recognition for a group of younger and older adults with normal hearing and a group of older adults with hearing impairment in various types of background maskers. The authors hypothesize that, as the masker condition becomes more difficult listening effort will increase, but the increase will be greater for older participants than for younger participants.
A dual-task paradigm was used to objectively evaluate listening effort. The primary task required participants to repeat sentences presented in three different background-masker conditions: (1) two-talker (TT), (2) six-talker, and (3) speech-shaped noise (SSN). The secondary task was a Digital Visual Pursuit Rotor Tracking test, 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 of the two tasks was separately and concurrently presented at a fixed overall 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 (i.e., very difficult) to 100 (i.e., very easy). Last, participants completed a battery of cognitive tests that measured working memory (Reading Span Test), processing speed (Digit Symbol Substitution Test), and selective attention (Stroop Test) ability.
Results revealed that participants’ working memory and processing speed abilities were significantly related to their speech-recognition performance in noise in all three background-masker conditions. Participants rated the TT condition to be the most difficult listening condition and the SSN condition to be the easiest listening condition. Both groups of older participants expended significantly more listening effort than younger participants did 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-talker masker condition compared with the SSN condition. Participants’ listening effort expended on the TT and SSN masker conditions was significantly correlated with their working memory and processing speed performance.
Findings from the present study indicate that older adults require more cognitive resources than younger adults to understand speech in background noise.