Efficient design of non-uniform cosine modulated filter banks for digital hearing aids

In this paper, efficient and simple designs of non-uniform filter banks for digital hearing aid applications are proposed. Hearing aids should be individually tuned to satisfy the requirements of hearing impaired persons. Cosine modulated filter banks are one popular filter bank having simple design procedure with efficient implementation structure. In the proposed structure for hearing aid, non-uniform subbands are obtained using two methods. The first method is by merging the adjacent channels of a uniform filter bank and the second method, is by using transition filters between two filters with different bandwidths. The advantages of the proposed structure are simple design procedure, less implementation complexity, greater flexibility in tuning the subbands for various types of audiograms and improved performance in terms of matching error.