Design Details

Testing and Results



The Group




We successfully modeled a digital hearing aid in MATLAB by implementing a noise reduction filter, frequency shaper and an amplitude shaper for a given speech signal.

Ways To Extend Our Project:
We used a simple model, and there are many other advantages of digital hearing aids that can be realized besides gain processing and digital noise reduction. Further ways to improve digital hearing aids include Digital Feedback Reduction, which can be implemented to reduce or eliminate moderate feedback through the use of a cancellation system or notch filtering. Directional Hearing Aids can also be implemented to improve the signal-to-noise ratio provided to the listener. For our project further study could include filtering out other types of noise in a given speech signal besides white Gaussian noise. Other types of noise include periodic noise, reverberation, and colored noise. The filters we used work best in a time invariant system. Therefore, we could improve our system by using adaptive filters, which are very useful in filtering noise in a constantly varying environment. Another possible improvement would be to implement the hearing aid in real time.

Other Applications:
The applications of the filters that we implemented extend far beyond use solely in digital hearing aids. We can use these filters in telecommunication systems such as satellites and cell phones, in image processing, or in any place where there is sensitivity to high frequencies or loud noises.