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
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.