Children's speech recognition scores: The speech, intelligibility index and proficiency factors for age and hearing level

Objective. The objective of this study was to predict consonant recognition scores of adults, children, and children with hearing impairment, using the Speech Intelligibility Index (SII). It was hypothesized that an adult-derived transfer function would be insufficient to predict the scores for children, and that transfer functions for normally hearing listeners would be insufficient to predict scores for children with hearing impairment. Proficiency corrections for age and hearing loss were explored. Design: A 21-consonant test of speech recognition was applied across five signal to noise ratios in a forced choice procedure. Four adults (aged 27-32 yrs), 15 children with normal hearing (aged 6.6-16.9 yrs), and 14 children with mild to severe hearing loss (aged 7.5-18 yrs) participated. The SII was computed for each listener and each test condition using the one-third octave band method. Transfer functions were fitted to the data of each group. Results: The adult-derived transfer function over-predicted the children's scores. Significant increases in prediction accuracy were obtained when the effects of age and hearing loss were incorporated into the transfer function as proficiency factors. Conclusions: The SII could successfully be used to predict speech recognition scores for both adults and children, once the effects of age and hearing loss were included in the development of a transfer function. Specific proficiency factors developed here may not generalize to other data sets. Nonetheless, the results shed light on factors to consider when using the SII to predict children's speech recognition scores.