Abstract: The auditory system is a very sensitive and complex network. Diseases, drugs, noise, trauma and aging may have resulted in varying degrees of hearing loss, which makes hearing impairments one of the most common sensory disturbances in the world. The most effective way to compensate hearing loss is to employ a hearing aid system which is an integration of voice amplification, noise reduction, feedback suppression, automatic program switching, environmental adaptation, and etc. The basic function of a hearing aid system is to amplify sounds selectively and then transfer the processed signal to the ear. The processed signal which is transferred to the ear enables the deaf people to hear the voice of the person who is near to them.

Keywords: Filter bank, Audiometer, ATMEL89S52 microcontroller, BAHA, Watch dog timers.