Delay Efficient Cosine Modulated Reconfigurable Filter Bank for Digital Hearing Aids targeting Noise Induced Hearing Loss

In this paper, an efficient architecture for cosine modulated reconfigurable filter bank with sectional reconfigurability is proposed for Digital Hearing Aids targeting Noise Induced Hearing Loss. Polyphase implementation of the prototype filter with shared modulation coefficients reduces the computational complexity and increases the tuning flexibility. The proposed architecture can be used for frequency compensation of different classes of audiograms while keeping the group delay minimum. The proposed filter bank can provide 1296 different frequency band distribution schemes based on external control signals according to the nature of the audiogram. The architecture is based on a 16-band cosine modulated filter bank with dynamic mering of bands based on audiogram. The flexibility of the filter bank allows matching most of the audiograms including low or moderately sloping SNHL and NIHL with notch at the center of frequency range. For all the standard audiograms considered for evaluation, the proposed design has acceptable matching errors. The group delay is very less compared to existing reconfigurable filter banks, which provide room for accommodating other DSP algorithms in sophisticated Digital Hearing Aids. The hardware resources required for implementation are comparable with other reconfigurable filter banks designed for the same application.