Filter banks for hearing aids applying subband amplification: A comparison of different specification and design approaches

Hearing instruments employ filter bank systems (FBS) to subdivide the microphone signal into subband signals. To reduce overall computation, decimation is applied, which inevitably induces disturbance. First, these effects are analysed in detail. Then, we postulate application specific FBS requirements in view of extensive subband signal amplification. Next, we compare four different prototype filter specification and design approaches for oversampling complex-modulated FBS with respect to the postulated requirements. Finally, we present design examples applying these approaches. Thus, we explicitly demonstrate the impact of subband signal amplification on the FBS characteristics.