An FPGA Implementation of Cochlear Implant Using Biorthogonal Wavelets

The toughest challenge for hearing aid designers is the implementation of hearing aid devices that fulfill the increased demand of hearing aids wearer such as low cost, low power consumption, small size, etc., while keeping high performance and device intelligibility. This paper presents a VLSI implementation for the speech processing module used in cochlear implants on Digilent XUP II Virtex-II Pro system. The on chip AC'97 audio codec LM4550 is used for analog to digital of the input speech signal. The system is implemented in software using the soft core processor MicroBlaze from Xilinx, which is used for running the speech processor and cooperating with other peripheral modules. The speech processor coding strategy is based on biorthogonal wavelet packets for frequency decomposition. The wavelet speech processing unit (WSPU) is implemented on FPGA using VHDL and then integrated into the processor system as a custom peripheral. To test the performance of the proposed design the obtained results are compared with the results obtained from Matlab by illustrating a sample of the channel outputs. The proposed design achieves low computational complexity and realtime processing.