Speech Intelligibility Index (SII) and variation of speech signal intensity in hearing impaired children

ABSTRACT

Purpose

To compare aided speech intelligibility index (SII) values in different speech signal inputs (75, 65, and 55 dBNPS), generated from the verification process of hearing aids, under different hearing loss severities and configurations.

Methods

41 children aged between three and 80 months old were selected, totalizing 78 ears (after exclusion of four ears). Hearing loss was classified according to audibility groups and SII intervals. Two hundred and thirty-four (234) SII values were analyzed as per speech stimulus and with regard to groups and audibility intervals.

Results

Movement of audibility groups along SII intervals was observed, which indicates variation associated with the input signal intensity, as well as with the distance between the sound source and the hearing aid microphone. Two equations were generated to predict SII values from input signal SII65.

Conclusion

Lower levels of speech stimulus sound pressure produce lower levels of speech intelligibility. This difference is more pronounced in hearing-impaired persons, who present SII values between 36 and 55%.

Keywords:
Speech intelligibility; Hearing aids; Hearing loss; Children; Rehabilitation of hearing-impaired persons