Effect of release time in compression hearing aids: paired-comparison judgments of quality.

Paired-comparison judgments of quality were obtained from 20 hearing-impaired listeners for speech processed through simulated compression hearing aids varying in release time (60, 200, 1000 ms) at three different compression ratios (1.5, 2, 3:1) and for three different background noises (ventilation, apartment, cafeteria). Analysis revealed that the main effect of release time did not have a significant effect on perceived quality. The interaction between release time and noise type was found to be significant. While no significant difference in preference for release times was evident for the ventilation noise, the longer release times (200 and 1000 ms) were preferred for the higher level noises (apartment noise, cafeteria noise). Post hoc testing revealed that the mean preference scores for the 200- and 1000-ms release time were significantly greater than that of the 60-ms release time with the competing cafeteria noise (p < 0.05). Analysis of individual subject data revealed statistically significant preferences that differed from the group mean, suggesting that individualized fitting of this parameter of a compression hearing aid might be warranted.