Phoneme recognition in modulated maskers by normal-hearing and aided hearing-impaired listeners

This study measured the influence of masker fluctuations on phoneme recognition. The first part of the study compared the benefit of masker modulations for consonant and vowel recognition in normal-hearing (NH) listeners. Recognition scores were measured in steady-state and sinusoidally amplitude-modulated noise maskers (100% modulation depth) at several modulation rates and signal-to-noise ratios. Masker modulation rates were 4, 8, 16, and 32 Hz for the consonant recognition task and 2, 4, 12, and 32 Hz for the vowel recognition task. Vowel recognition scores showed more modulation benefit and a more pronounced effect of masker modulation rate than consonant scores. The modulation benefit for word recognition from other studies was found to be more similar to the benefit for vowel recognition than that for consonant recognition. The second part of the study measured the effect of modulation rate on the benefit of masker modulations for vowel recognition in aided hearing-impaired (HI) listeners. HI listeners achieved as much modulation benefit as NH listeners for slower masker modulation rates (2, 4, and 12 Hz), but showed a reduced benefit for the fast masker modulation rate of 32 Hz.