Comparison of hearing aids with amplitude compression

Abstract

Intelligibility tests using a Modified Rhyme Test were performed with commercially available hearing aids with various values of time constants of compression and of harmonic distortion during overshoots. For normal‐hearing subjects, signal‐to‐noise ratios of −2 and +2 dB were used. Subjects with sensorineural hearing impairment listened in quiet at their most comfortable listening level and at two additional sound‐pressure levels (10 and 20 dB lower than the first one). Different hearing aids affected the performance of both groups of listeners similarly. At low signal‐to‐noise ratios or low sound‐pressure levels, better performances were observed for shorter time constants of compression and larger compression ratios. At higher signal‐to‐noise ratios or higher sound‐pressure levels, the occurrence of harmonic distortion during overshoots deteriorates the performance, with greater deterioration occurring for impaired hearers than for normal hearers. [This research was supported by the NIH Biomedical Sciences Support Grant (FH 07088) and by the Prosthetic and Sensory Aids Service of the Veterans Administration.]