Efficient representation of short-time phase based on group delay

An efficient representation of short-time phase characteristics of speech sounds is proposed, based on findings which suggest the perceptual importance of phase characteristics. Subjective tests indicated that the synthesized speech sounds by the proposed method are indistinguishable from the original speech sounds with a moderate data compression. The proposed representation uses lower-order coefficients of the inverse Fourier transform of the group delay of speech. It also alleviates the voiced/unvoiced decision, which is an indispensable part in conventional speech coding algorithms. These features make our method potentially very useful in many applications like speech morphing.