An improved decomposition method for WI using IIR wavelet filter banks

In this paper, we present an alternative characteristic waveform (CW) decomposition mechanism for the Waveform Interpolation (WI) paradigm based on the Pitch Synchronous Wavelet Transform (PSWT). In this technique, IIR filters replace the conventional FIR filters of the PSWT, offering computational and spectral magnitude performance advantages, in addition to significant delay reductions. Previously, the PSWT has only incorporated filter banks with slowly reacting FIR wavelet filters. While these filters possess the desirable properties of linear phase, and design simplicity, a large delay is incurred which increases exponentially with increasing resolution. The progression to IIR filter banks gives rise to a multi-resolution decomposition mechanism, beneficial for real-time applications, such as speech coding, where delay is an important issue.