Perceived sound quality in a hearing aid with vented and closed earmould equalized in frequency response.

Nine normal-hearing subjects listened to speech and music in a hearing aid, either through a vented earmould or a closed earmould. The complex frequency responses of the two systems were made equal by compensating the aid and closed mould combination with a digital filter. The subjects rated the perceived sound quality of the systems on seven perceptual scales and a scale for overall impression. The results of the ratings support the hypothesis that there is no difference in perceived sound quality between vented and closed earmoulds that are equalized in frequency response, provided that the perceived loudness is the same in both cases.