Evaluation of hearing-assistive devices

Abstract

　We evaluated speech intelligibility and sound impression with hearing aids in a noisy classroom between subjects with and without hearing-assistive devices. Test sounds were recorded through hearing aids worn on HATS (Head And Torso Stimulator), and presented to 30 normal hearing subjects. Monosyllables were used for measuring the intelligibility scores and short sentences for evaluating speech impression. These tests were conducted under both noisy and quiet conditions. Two types of hearing aids, one equipped with a noise suppression function and the other with no setting for noise suppression. The hearing-assistive devices used in the test included 2 FM systems, one, an FM transmitter equipped with a setting for noise suppression, and the other, without such a setting, and 1 induction loop system. The intelligibility score was analyzed by the percentage of corrected monosyllable answers, and the semantic differential scores of hearing impressions were analyzed by factor analysis. Subjects with hearing aids equipped with a noise suppression function showed significantly higher intelligibility scores and positive sound impressions, regardless of whether the environment was noisy or not. The intelligibility scores improved significantly and the differences in the intelligibility scores and speech impressions between subjects with the two types of hearing aids decreased after the introduction of hearing-assistive devices; higher intelligibility scores were obtained with the induction loop system. Factor analysis showed semantic differential scores with different features with each of the hearing-assistive devices.