A channel vocoder using wavelet packets on a reconfigurable device

A channel vocoder using wavelet packets for computer music applications is proposed. The input audio signals are a modulating voice and a carrier melody. The wavelet packets channel vocoder transforms windowed frames of both signals to a subband domain, mixes the melody with the voice envelope, and transforms back the result to the original domain. Design is performed with Matlab/Simulink tools and real time implementations with Pure Data and Virtex II Pro FPGA board. Appropriate choices of frame length, wavelets, decomposition levels and envelope detector filter are proposed to achieve good quality sound effects. Finally, guidelines to improve transmission and compression rates in a future work are suggested.