Frequency resolution and phoneme recognition by hearing-impaired listeners

The relationship between auditory frequency resolution and speech perception was investigated in 11 hearing-impaired listeners who differed widely in terms of hearing-loss severity, hearing-loss configuration, and frequency resolution abilities. First, the function relating articulation index (AI) to percent correct phoneme recognition was determined for 19 normal-hearing listeners at a variety of speech levels and S/N ratios. Eleven hearing-impaired subjects were then tested with the same speech materials throughout a wide range of AI conditions. Simultaneous-masked psychophysical tuning curves were also obtained at probe frequencies of 0.5, 1, 2, and 4 kHz from all hearing-impaired subjects. When phoneme recognition scores were weighted by AI, the performance of 10 of the 11 hearing-impaired subjects was within normal limits. A modest correlation was observed between high-frequency tuning curve slope and the error in the AI prediction relative to the normal AI data. Results indicate that although listeners with poor frequency resolution tend not to be able to extract as much information from the acoustic speech signal as normally hearing listeners, their phoneme recognition abilities are nevertheless not greatly diminished. [Work supported by NIDCD DC00110.]