Effect of Number of Channels and Compression Parameter in Hearing Aids on Music Perception

Abstract

Appreciation of music is the next most commonly expressed requirement after speech by the users of hearing aids. Use of hearing aids brings about improvement in perception of speech. However, this may not apply for music. The present study attempted to evaluate the effects of varying the number of channels and compression knee-point on perception of music. This was done in individuals with flat (N=12) vs. sloping (N=12) mild-moderate sensorineural hearing loss. Music perception in these individuals was assessed using the Music Perception Test Battery (MPTB) and a five-point perceptual rating scale using the default setting for music vs. the high knee-point of compression setting, for the two and eight channel hearing aids. The results indicated that, for most of the parameters, there was no significant difference between the two groups (flat vs. sloping) or the channels (two vs. eight). However, significant difference was observed between the hearing aid settings (default vs. high knee-point of compression) for both the hearing aids (two vs. eight channels); with the performance on most of the parameters tested being better when the knee-point of compression was high. This result is in agreement with studies which stated that the compression knee-point for music should be set 5 to 8 dB higher than for equivalent intensities of speech, as the crest factor for musical instruments is 18 to 20 dB. This prevents the music from forcing the hearing aid to operate in its non-linear mode prematurely.