Multiplexer based Power Saving Flexible Filter Bank for Digital Hearing Aid applications

Power drain is one of the common issue in almost all electronic gadgets. Here a multiplexer based power efficient filter bank is presented. Digital Hearing aid design requires a bank of filters that provides reasonable audiogram matching for a specific case of hearing loss. Many a fixed and reconfigurable filter banks are reported for different types of sound wave decomposition plans for audiogram matching. But the delay and hardware complexity of these structures are relatively large for a compact hearing aid system. In this paper, a minimum phase constrained least square finite impulse response filter bank with reduced group delay and with hardware flexibility is proposed. Minimum phase FIR filter shows least passband group delay among the group of stable filters with same magnitude response characteristics and the coefficients required for filter is only half of that of the prototype finite impulse response filter. Multiplications per sample is considerably reduced in this method and is suitable for systems where the spectra of desired and noise signals are overlapped. The proposed filter bank can operate in two modes. In one mode the number of filters per bank is seven and in the other power saving mode it is six. Synthesis result of the proposed design is also presented.