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

This study was a double blind comparison of three types of hearing aid circuits: Class A linear peak clipping, Class D compression limiting and K-Amp wide dynamic range compression. Subjective ratings, speech perception tests, real ear measurements and questionnaire data were obtained from a group 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, even in the presence of high levels of speech and noise. Our primary conclusions include recommending K-Amps to new hearing aid users with mild to moderate hearing loss, mostly on the basis of battery life, while cautioning about the use of compression knee-point controls and recognizing that Class A and Class D amplifiers are virtually equivalent in every performance measurement.