Speech perception in gated noise: the effects of temporal resolution.

Previous investigations have suggested that hearing-impaired (HI) listeners have reduced masking release (MR) compared to normal hearing listeners (NH) when they listen in modulated noise. The current study examined the following questions that have not been clearly answered: First, when HI listeners are amplified so that their performance is equal to that of NH listeners in quiet and in steady noise, do HI listeners still show reduced MR with modulated noise when compared to NH listeners? Second, is the masking release the same for sentences and CV syllables? Third, does forward masking significantly contribute to the variability in performance among HI listeners? To compensate for reduced hearing sensitivity for HI listeners, the spectrum levels of both speech and noise were adjusted based on the individual hearing loss. There was no significant difference between the performance of NH listeners and that of HI listeners in steady noise and in quiet. However, the amount of MR for sentences and for CV syllables was significantly reduced for HI listeners. For sentence recognition, the amount of MR seemed to be more related to hearing sensitivity for low-to-mid frequencies than to forward masking. In contrast, forward masking thresholds appear to be a major contributor to the amount of MR for syllable recognition.