Uniform polyphase filter banks for use in hearing aids: Design and constraints

Signal processing in hearing aids for purposes such as hearing loss compensation or noise reduction requires transforming the input signal into frequency bands. Additional audiological constraints need to be considered to accurately model the hearing loss compensation as well as to prevent unintended artefacts. This necessitates highly efficient solutions with low delay, strong alias suppression and sufficient frequency resolution. After discussing requirements from several aspects, we show how uniform polyphase filter banks can be designed to meet these requirements. One important topic is a prototype filter design, for which we present numerically optimized solutions. Finally, we show results for quantized filter coefficients.