A new approach to the excitation problem for CELP coder is presented. A generalized codebook of excitation vectors is proposed, consisting of pulses (as in MP coders), stochastic sequences (as in classical CELP coders) and past excitation sequences (as in SEV). The resulting excitation is a linear combination of a small number of these vectors. No constraints are imposed on the type of selected vectors, the only criterion is a distance between the original and synthetic speech signals (both passed through the perceptual filter). Two algorithms for selection of codebook vectors and computation of gains are described. Some results of simulations are reported and problems of complexity and implementation are discussed.
Bibliographic reference. Moreau, N. / Dymarski, P. (1989): "Mixed excitation CELP coder", In EUROSPEECH-1989, 1322-1325.