Design and implementation of reconfigurable digital filter bank for hearing aid
S. Anso Raj, Athira Shaji · 2016
A hearing aid is an electroacoustic device for improving the hearing ability of hearing impaired. In a simple hearing aid gain is applied to the whole input frequency range, due to which the intensities of some speech sounds after amplification will be larger than the discomfort thresholds. To solve this problem a highly reconfigurable non-uniform digital FIR filter bank structure is proposed, where the whole frequency range is divided into several subbands and each subband has its own amplification coefficient. The non-uniform spaced subbands can be realized with Variable Bandwidth Filters (VBF). Each VBF can be realized as a combination of arbitrary sample rate converters and FIR filter. The Distributed Arithmetic (DA) based FIR filter is a wise choice where all the multiplications and additions are replaced by a lookup table and shifter-accumulator. The proposed architecture uses a multiplier less structure, where the sample rate converters are realized using Cascaded Integrator Comb (CIC) filters and the FIR filter uses Distributed Arithmetic. The use of multiplier less structures leads to significant decrease in area and power consumption. The FPGA platform offers flexible, denser, faster and more power efficient solutions and hence the overall structure can be efficiently implemented using FPGA., Variable Bandwidth Filters, cascaded integrator comb (CIC) filters, Distributed Arithmetic (DA), FPGA.