Effects of signal bandwidth on listening effort in young- and middle-aged adults.

The purpose of this study was to assess the effects of signal bandwidth, noise and signal predictability on listening effort among younger and middle-aged individuals with normal hearing, where YNH = young normal hearing and ONH = older normal hearing. It was of interest to determine if a reduction in high-frequency energy would differentially influence performance between the two groups. A mixed-model design was used, where listening effort, word identification and effort ratings served as the within-subject factors and listener group served as the between-subject factor. Twenty listeners aged 18-25 years (YNH group) and 20 listeners aged 40-55 years (ONH group) participated in the experiment. Results showed significantly poorer word recall and significantly higher perceived effort among the ONH group. Increasing the signal bandwidth from 2 to 8 kHz significantly improved word recall and decreased listening effort ratings. Effort ratings from both groups matched word recall performance in that when word recall was lower perceived effort was higher and when word recall was higher perceived effort was lower. In general, providing additional high-frequency energy up to 8 kHz reduced listening effort among both groups of listeners. However, the ONH group, experienced additional effort when completing the tasks.