A systematic ANSI S1.11 filter bank specification relaxation and its efficient multirate architecture for hearing-aid systems

Recently, emerging mobile computing requires the high integration of hearing aids into a single system-on-chip. Modern hearing aid systems include a frequency decomposer, noise reduction, feedback cancellation, auditory compensation, and intelligent adaptation. The majority of existing works concentrated on improving the performance and efficiency on a single-signal processing block or one-sided effect. These works lacked comprehensive discussions on system-wide aspects regarding the overall impacts. To design an optimal hearing aid system, frequency decomposers, or the filter banks that dominate in hearing aid systems, are the first priority. We propose a systematic relaxation of the ANSI S1.11 specification and its design procedure for filter banks. The proposed design procedure overcomes the drawbacks of previous works and changes the five performance indices of the filter bank: delay, complexity, sub-band rate reduction, ripples of synthesized output, and prescription matching errors. These performance indices help system or algorithm designers in selecting a beneficial system-relaxed filter bank to achieve optimal hearing aids. The proposed multirate filter bank using the resampling method provides an efficient, low complexity, and delay-constrained computing architecture. Finally, seven design cases are used to demonstrate the proposed method, and comprehensive discussions of the five performance indices are presented.