Computationally efficient stochastic coding of speech

Issues of codebook excitation and the long-term synthesis filter are addressed. To deal with the excitation complexity, a codebook structure and an alternative search technique are developed for the excitation codebook that significantly lower the complexity with very little loss in quality and compare favorably with other recent alternative techniques. This allows a reasonable implementation complexity with very little loss in quality compared to a standard exhaustively-searched block codebook. An efficient method to improve the long-term prediction analysis by using a three-tap filter that requires little additional complexity is introduced. The result is a stochastic coder that provides high speech quality at 8 kb/s with manageable computational complexity