Speech morphing by independent interpolation of a spectral envelope and source excitation

A speech morphing algorithm based on progressive interpolation of spectral envelopes and source signals is proposed. The basic morphing scheme is; 1) determine the time correspondence for unit waveforms of original and target speech, 2) separate speech spectra into an envelope and a sound source, 3) obtain the frequency correspondence for spectral channels of original and target speech for each envelope, 4) interpolate both source signal and enve lope, 5) construct a unit waveform, and 6) generate morphing speech by PSOL A. In the objective test, the proposed method can reduce the spectral disto rtion by 1.9 dB in comparison with the method based on progressive substitu tion of spectra, when it is used for interpolating two vowels in a real spe ech. The effectiveness of the method is also confirmed by a subjective test in which 89% (male to female) or 93% (female to male) subjects preferred t he proposed method. (C) 1998 Scripta Technica, Electron Comm Jpn Pt 3, 82(3 ): 22-30, 1999.