Comparisons of speech recognition in noise by mildly-to-moderately hearing-impaired children using hearing aids and FM systems.

Four hearing aid arrangements (monaural-omnidirectional, monaural-directional, binaural-omnidirectional, binaural-directional) and a number of FM system-personal hearing aid combinations (including direct input, neck loop, and silhouette inductor--monaural and binaural--and environmental microphone on and off) were evaluated in a school classroom on nine children with mild-to-moderate sensorineural hearing losses. Two measures of speech recognition in noise were employed. First, the signal-to-noise ratio (S/N) yielding 50% identification of spondees was determined using a simple up-down adaptive procedure. Second, word recognition scores were obtained for three amplification arrangements at two different S/Ns (+6 and +15 dB). The average FM advantage over a personal hearing aid was equivalent to a 15-dB improvement in S/N. Activation of the hearing aid microphone caused most of the FM advantage to disappear. The benefit offered by the FM system decreased as the environmental S/N increased but remained significant even at +15 dB. Significant improvement also was found with the use of directional as compared to omnidirectional microphones, both in the hearing aids and FM teacher microphone.