A low complex 10-band non-uniform FIR digital filter bank using frequency response masking technique for hearing aid

Abstract

This paper presents a low complex design of a non-uniformly spaced digital finite impulse response (FIR) filter bank for digital hearing aid application. Frequency response masking (FRM) technique is used for the implementation of 10 non-uniformly spaced subband filters. FRM technique ensure the drastic reduction in the number of multipliers and adders in linear phase FIR filter. It employs two half-band filters as prototype filters, which leads to significant savings in terms of arithmetic operations. Further reduction can be achieved by using a masking filter with minimum order. The simulation result shows that the proposed filter bank with stop band attenuation of 80 dB can be achieved with 10 multipliers. The audiogram fitting with the selected audiogram gives a maximum matching error of 2 dB. From the audiogram matching result, it can be seen that the introduction of non-uniformly spaced filter bank improves the audiogram matching especially for sharp transition in hearing losses at low and high frequencies.