Occlusion reduction system for hearing aids with an improved transducer and an associated algorithm

Many of hearing aid users have complained about discomfort of their own voice and/or the mastication sound. Such discomfort is caused by increased sound pressure at low frequencies when the ear canal is blocked by hearing aid itself. This phenomenon is called "occlusion effect" and is one of the critical issues for hearing aids. This report proposes an occlusion reduction system based on active noise control technique using a new acoustic transducer. The proposed system can reduce the increased sound pressure in the ear canal about 26 dB around 200 Hz. While the proposed system achieved a better performance in the reduction, some distorted sounds are frequently perceived through the system. This secondary issue of the distorted sounds can also be reduced by controlling the feedback loop gain. Finally, a prototype system with the new transducer and a distortion suppressor algorithm is developed and then evaluated.