Vector adaptive coding method for speech and audio

Frames of vectors of digital speech samples are buffered (11) and each frame analyzed to provide gain (G), pitch filtering (QP,QPP), linear-predictive coefficient filtering (QLPC) and perceptual weighting filter (W) parameters. Fixed vectors are stored in a VQ codebook (13). Zero-state response vectors are computed from the fixed vectors and stored in codebook (14) with the same index as the fixed vectors. Each input vector (sn) is encoded by determining the index of the vector in codebook (13) corresponding to the vector in codebook (14) which best matches a zero-state response vector (vn) obtained from the input vector (sn) and the index is transmitted together with side information representing the parameters. The index also excites LPC synthesis filter (15) and pitch prediction filter (16) to produce a pitch prediction (ŝn) of the next speech vector. A receiver has a similar VQ codebook and decodes the side information to control similar LPC synthesis and pitch prediction filters to recover the speech after adaptive post-filtering.