Acoustic cues for lexical tone perception in hearing-impaired listeners

Abstract

This series of studies was aimed to investigate how listeners with sensorineural hearing loss (SNHL) and with auditory neuropathy syndrome disorder (ANSD) achieved lexical tone recognition using either the temporal envelope (E) or the fine structure (FS) cues. Five groups of Mandarin-speaking subjects, including (1) 22 normal-hearing subjects, (2) 8 moderate, (3) 13 moderate to severe, (4) 10 severe SNHL patients with various degrees of SNHL, and (5) 10 patients with ANSD, participated in the study. Monosyllabic words were processed through a 16-channel “auditory chimera” in which E from a monosyllabic word of one tone was paired with FS from the same monosyllable of other tones. On average, 92.0%, 67.4%, 58.1%, 37.5%, and 17.1% of the tone responses were consistent with FS cues, while 5.8%, 23.7%, 31.1%, 45.2%, 42.7% of the tone responses were consistent with E cues for the 5 groups of subjects mentioned above. Therefore, as the hearing loss becomes more severe, the ability of SNHL patients to use FS for tone recognition becomes more deteriorated. The ability of ANSD subjects to use FS is even poorer than patients with severe SNHL even though their pure-tone thresholds were only moderately elevated in the low and mid frequencies.