Selective-LPC based representation of STRAIGHT spectrum and its applications in spectral smoothing

In this paper we propose a new method to represent STRAIGHT spectrum. The new method provides STRAIGHT spectral parameters with the capability of interpolation and quantization, which is needed for most speech manipulation, especially for spectral smoothing. The proposed method estimates 2-band selective-LPC whose spectral envelope fits the given STRAIGHT spectrum. With the interpolation properties of LSP, the estimated selective-LPC could be converted to LSP and then simply interpolated. We apply this representation in our spectral smoothing experiments and the results show that this method can get smooth spectral envelope over the segment boundaries. Listening tests prove that this algorithm effectively smooth speech boundaries with little quality degradation.