Interpolation of LPC spectra via pole shifting
Vladimir Goncharoff, M. Kaine-Krolak · 2002
Interpolation of linear predictive coded (LPC) spectra is applied in a variety of speech processing tasks. We present a new method for interpolating between LPC spectra via pole-shifting. This approach solves the problem of real-to-complex and complex-to-real pole transitions by converting to a domain where each pole has a complex conjugate. Desired pole shifts are calculated in the new domain after applying a perceptually-based pole pairing algorithm. Intermediate spectra corresponding to these pole transitions are then optimally approximated using the original number of poles. The resulting interpolated spectral sequence is characterized by approximately linear changes in formant frequencies and bandwidths, and is free of the artifacts that may occur with other LPC spectral parameter interpolation methods.