The Speech Intelligibility Index and the Pure-Tone Average as Predictors of Lexical Ability in Children Fit With Hearing Aids

Abstract

To determine whether a clinically obtainable measure of audibility, the aided Speech Intelligibility Index (SII; American National Standards Institute, 2007), is more sensitive than the pure-tone average (PTA) at predicting the lexical abilities of children who wear hearing aids (CHA). School-age CHA and age-matched children with normal hearing (CNH) repeated words and nonwords, learned novel words, and completed a standardized receptive vocabulary test. Analyses of covariance allowed comparison of the 2 groups. For CHA, regression analyses determined whether SII held predictive value over and beyond PTA. CHA demonstrated poorer performance than CNH on tests of word and nonword repetition and receptive vocabulary. Groups did not differ on word learning. Aided SII was a stronger predictor of word and nonword repetition and receptive vocabulary than PTA. After accounting for PTA, aided SII remained a significant predictor of nonword repetition and receptive vocabulary. Despite wearing hearing aids, CHA performed more poorly on 3 of 4 lexical measures. Individual differences among CHA were predicted by aided SII. Unlike PTA, aided SII incorporates hearing aid amplification characteristics and speech-frequency weightings and may provide a more valid estimate of the child's access to and ability to learn from auditory input in real-world environments.