Speech perception in gated noise: The effects of spectral/temporal resolution and auditory integration

Previous investigations have suggested that listeners with hearing impairment (HI) have reduced masking release (MR) compared to normal hearing listeners (NH) when they listen in modulated noise. However, they have not compared HI and NH listeners' performance when the performance levels of the two groups were equal in steady noise and in quiet. Furthermore, these studies have not fully evaluated suprathreshold factors that are thought to contribute to masking release. Also, MR has been measured using sentence materials in some investigations, and using CV syllables in others. The purpose of the current study was to more thoroughly examine MR in HI listeners using both syllable and sentence materials, and to relate the amount of MR to hearing threshold and suprathreshold abilities of forward masking, auditory filter bandwidth, and auditory stream segregation/integration. Nine HI and 8 NH young adults participated in this study.; In order to compensate for reduced hearing sensitivity for HI listeners, the spectrum levels of both speech (IEEE sentences and CV syllables) and noise were adjusted based on the degree and configuration of 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 as well as the characteristics of auditory filters. Performance for gated sentence recognition was also strongly correlated with sentence recognition in gated noise. In contrast, forward masking thresholds appear to be the main contributor to the amount of MR for syllable recognition. The results of traditional auditory streaming tasks were not a good predictor for either sentence or syllable recognition.