Comparisons in consonant confusions with and without gain for the hearing-impaired listeners

Purpose: The present study aimed determining the effect of audibility on a consonant-byconsonant perception and on perceptual confusions per hearing-impaired (HI) listener. Methods: Six participants with sensorineural hearing loss participated. Sixteen consonantvowel (CV) syllables with the common vowel /a/ were presented as a function of signal-tonoise ratio. Gains were computed with subject's hearing thresholds by using National Acoustics' Laboratory - Revised Compensation Rule. Then the gains were applied to each of the 16 CV syllables. Consonant confusions were measured without and with gain. Results: We identified three levels of difficulty in CV perception regardless of applying gain: Easy- /ga/, /ka/, /ma/, /na/, /pa/, /?a/; Moderate - /da/, /fa/, /sa/, /ta/, /3a/, /za/; Difficult- /ba/ /va/, /da/, and /?a/. Enhanced audibility improved performance most for Moderate set and little for the Easy set, but created negative effect on performance for the Difficult set. The effect of gain is also listener-specific: three out of the six listeners received benefit while other three listeners experienced negative effect from CVs with gain. The confusion analysis showed that subjects who benefited had the same primary competitors between gain and no-gain conditions, while subjects who did not benefit had additional competitors with gain. Conclusions: The preliminary results of this study indicate that audibility is one of the primary factors influencing speech recognition of HI listeners, but reduced audibility alone cannot explain the difficulty of HI listeners to understand speech-in-noise. A more affirmative conclusions can be made with further analyzing data from larger sample size.