Double blind comparison of three hearing aid circuits with new hearing aidusers

This study was a double blind comparison of three types of hearing aid circ uits: Class A linear peak clipping, Class D compression limiting and K-Amp( TM) wide dynamic range compression. Subjective ratings, speech perception t ests. real ear measurements and questionnaire data were obtained from a gro up of 17 new hearing aid users with mild to moderate sensorineural hearing loss. The results indicate a similar performance for all three circuits. We saw no evidence of performance degradation due to saturation distortion, e ven in the presence of high levels of speech and noise. Our primary conclus ions include recommending K-Amps(TM) to new hearing aid users with mild to moderate hearing loss, mostly on the basis of battery life, while cautionin g about the use of compression knee-paint controls and recognizing that Cla ss A and Class D amplifiers are virtually equivalent in every performance m easurement.