Combining temporal-envelope cues across channels: effects of age and hearing loss.

The goal of this study was to examine the ability to combine temporal-envelope information across frequency channels. Three areas were addressed: (a) the effects of hearing loss, (b) the effects of age and (c) whether such effects increase with the number of frequency channels. Twenty adults aged 23-80 years with hearing loss ranging from mild to severe and a control group of 6 adults with normal hearing participated. Stimuli were vowel-consonant-vowel syllables. Consonant identification was measured for 5 conditions: (a) 1-channel temporal-envelope information (minimal spectral cues), (b) 2-channel, (c) 4-channel, (d) 8-channel, and (e) an unprocessed (maximal spectral cues) speech condition. Performance of listeners with normal hearing and listeners with hearing loss was similar in the 1-channel condition. Performance increased with the number of frequency channels in both groups; however, increasing the number of channels led to smaller improvements in consonant identification in listeners with hearing loss. Older listeners performed more poorly than younger listeners but did not have more difficulty combining temporal cues across channels than in a simple, 1-channel temporal task. Age was a significant predictor of nonsense syllable identification, whereas amount of hearing loss was not. The results support an age-related deficit in use of temporal-envelope information with age, regardless of the number of channels.