Abstract: As hearing aids partially overcome auditory deficits and normally employed for the hearing impaired people to compensate loss in hearing.This paper mainly focus to design a simulink based model which have a digital filter bank which can separate the input speech signal into different bands and automatically gain is adjust for individual band. The design model consists of analog to digital (A/D) converter, digital filter bank, gain control block, compressor and digital to analog (D/A) converter. The A/D converter converts the analog speech signal into a digital speech signal. Further the input speech signals gets process by digital filter bank and its gain is adjusted. As we know that for a person with hearing impairment the range of threshold levels between weakest sound that can be heard and the most intense sound that can be tolerated is less than normal listener. So, to compensate this factor, hearing aids amplify weak sounds more than they amplify intense sound. The D/A will convert the output processed signal into analog speech output signal. The speaker converts the analog speech signal into an acoustical output signal that is directed into ear canal of the hearing instrument user.
Keywords: Hearing aids, digital filter bank, gain control, compression.