UBC Theses and Dissertations
The effect of hearing aids on listening working memory span Douglas, Alvilda Myrel
The primary purpose of this study was to examine the effect of hearing aids on listening working memory for listeners who are hard-of-hearing. This was done by measuring participants' listening working memory spans, using the materials of the SPIN-R sentences, both with and without the use of hearing aids. Four men and four women with sensori-neural hearing loss participated in this experiment. All had unaided thresholds of 45 dBHL or better up to and including 1000 Hz, and wore bilateral hearing aids. Participants listened to sets of SPIN-R sentences. After each sentence, participants repeated the sentence-final word, and performed a judgment task relating to the sentence context. After each set of sentences, participants recalled the sentence-final words from that set. The largest set size for which participants could successfully recall all the sentence-final words at least three out of five times was taken as the measure of their listening working memory span, with an additional half-point if the participant successfully recalled all the sentence-final words at least two out of five times at the next larger set size. Participants performed this task both with and without their hearing aids and both in quiet and in the presence of background noise. It was found that neither the use of hearing aids nor the signal-to-noise ratio of the speech stimuli and background babble had a significant effect on participants' spans. There was nevertheless a trend for hearing aids to have a detrimental effect on span in quiet. Specifically, four of the eight participants had lower spans on the aided, quiet condition than on the unaided, quiet condition, while four had the same spans on these two conditions. The use of hearing aids was not found to have an effect on listening working memory span in noise. The detrimental effect of hearing aids in quiet is tentatively attributed to distortion introduced into the signal by the compression algorithms used in the hearing aids. Such distortion is proposed to increase processing demands on working memory. As the working memory system is theorized to allocate activation between processing demands and storage demands, an increase in processing demands due to amplification would reduce activation for storage and thus decrease listening working memory span. Working memory span is correlated with comprehension. Results from this study therefore indicate a potential cause for comprehension problems in listeners who are hard-ofhearing who use hearing aids.
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