Basic algorithm of pitch synchronous innovation CELP (PSI-CELP) speech coding

This paper proposes a new speech coding method called PSI-CELP (Pitch Synchronous Innovation CELP). This method is based on CELP, but adds pitch synchronous innovation, which means that even random codevectors are adaptively converted to have pitch periodicity for voiced frames. In addition, this paper also proposes four other methods: (a) a fixed codebook that is prepared as part of the adaptive codebook for nonperiodic frames, (b) a random codebook which consists of two conjugate sub-codebooks, (c) an MA-type perceptual weighting filter using unquantized LPC parameters, and (d) codebook searches using delayed decision. PSI-CELP improves the SNR, segmental SNR, and opinion equivalent Q value of the coding system by 1.6 dB, 1.0 dB, and 0.5 dB respectively.