Reducing noise leakage problem of open-fit hearing aid using active noise cancellation

The purpose of using hearing aids is to provide clear and loud enough sound for hearing loss patients. For long-time wearing, the more comfortable type, open-fit (open-air) hearing aids, have become popular in recent year. However, the open dome structure results in the noise leakage bypass the hearing aid toward the eardrum, which degrades the quality of listening perception of enhanced speech. Since the noise leakage cannot be correctly measured by the reference microphone of the hearing aid, it is unable to be canceled by the original function, such as noise reduction or speech enhancement, of hearing aid itself. Therefore, this paper proposes an active noise control (ANC) technique used in the open-fit hearing aid to deal with the noise leakage problem. The audio-integrated adaptive feedback FXLMS algorithm is implemented to play the enhanced speech and anti-noise at the same time without interfering each other. Besides, this paper also proposed a shaping filter to filter out the frequencies that patients cannot hear originally and make it more effectively without generating useless anti-noise.