Phoneme perception in temporally and spectrally modulated maskers: Effect of suprathreshold hearing impairment.

Abstract

Normal-hearing (NH) listeners show better speech recognition in fluctuating maskers than in steady-state (SS) maskers. Hearing-impaired (HI) listeners do not show such benefit due to elevated thresholds. With amplification, HI listeners show some benefit, but significantly less than that for NH listeners. To investigate the reduced benefit in HI listeners at suprathreshold levels, we measured consonant and vowel recognition by NH and aided HI listeners in the presence of SS and modulated maskers. The modulated noises were generated by modulating the SS noise, in either one or six channels, by either one talker speech or four talker babble, resulting in four different modulated masker conditions. HI listeners were provided individualized gain according to the Cambridge formula. Both NH and aided HI listeners showed reduced intelligibility for consonants and vowels due to increase in the number of talkers. Increase in the number of channels provided more benefit to NH listeners than to HI listeners, and this benefit was greater for vowels than for consonants. This benefit due to spectral modulations for aided HI listeners was not correlated with audibility, but seems to be correlated with their ERBs. [Work supported by the Oticon Foundation, Denmark.]