Perception of temporal fine-structure cues in speech with minimal envelope cues for listeners with mild-to-moderate hearing loss.

The contribution of temporal fine-structure (TFS) cues to consonant identification was compared for seven young adults with normal hearing and five young adults with mild-to-moderate hearing loss and flat, high- or low-frequency gently sloping audiograms. Nonsense syllables were degraded using two schemes (PM: phase modulation; FM: frequency modulation) designed to remove temporal envelope (E) cues while preserving TFS cues in 16 0.35-octave-wide frequency bands spanning the range of 80 to 8020 Hz. For both schemes, hearing-impaired listeners performed significantly above chance level (PM: 36%; FM: 31%; chance level: 6.25%), but more poorly than normal-hearing listeners (PM: 80%; FM: 65%). Three hearing-impaired listeners showed normal or near-normal reception of nasality information. These results indicate that for mild to moderate levels of hearing loss, cochlear damage reduces but does not abolish the ability to use the TFS cues of speech. The deficits observed for both schemes in hearing-impaired listeners suggest involvement of factors other than only poor reconstruction of temporal envelope from temporal fine structure.