A 16-Band Reconfigurable Hearing Aid using Variable Bandwidth Filters
A highly re-configurable non-uniform digital FIR filter bank structure is proposed for the hearing aid application. The non-uniform spaced sub bands are realized with variable bandwidth filters (VBF). Each VBF is implemented as a combination of two arbitrary sample rate converters and a fixed bandwidth FIR low pass filter and the same can be implemented in application specific integrated circuit (ASIC) for the general purpose application to correct any hearing loss pattern. The bandwidths of the channels to suit the optimized audiogram fitting, corresponding frequency shift and bandwidth ratio with respect to the fixed filter are the re-configurable parameters which need modification to achieve the re-configurability. The results of the tests on various hearing loss patterns show that with optimal selection of the band edges of each band, the proposed method achieves better matching between audiograms and the magnitude responses of the filter bank. The cost of hearing aid can be reduced. It can also be made reconfigurable with minimum modification in the programmable part.
