Relationship of aided speech recognition to hearing thresholds and aided speech-peak sensation levels in severely and profoundly hearing-impaired adults

The relationship of speech recognition to hearing threshold levels and to aided speech-peak sensation levels was examined in a group of severely and profoundly hearing-impaired adults. Closed-set vowel and consonant recognition tests were administered at the subjects' most comfortable levels. Both vowel and consonant recognition scores were relatively predictable from hearing threshold level at 2000 Hz, the correlations being -.84 and -.76, respectively. Recognition of most speech-feature contrasts was also predictable from hearing threshold levels, at one or two frequencies, always including 2000 Hz. The predictability of speech recognition was similar, but no better, from aided speech-peak sensation levels than from hearing threshold levels. Vowel and consonant scores were similar to or better than those reported in previous studies, possibly reflecting subject selection factors and/or extensive testing that was used to optimize hearing aid fittings. For the majority of subjects, altering the low-frequency response of the hearing aid did not significantly affect vowel or consonant recognition scores.