METHOD FOR GENERATING A SPECTRAL NOISE WEIGHTING FILTER FOR USE IN A SPEECH CODER

摘要

Analysis by synthesis calculates a difference by subtracting (130) synthesized s peech from input speech. The synthesized speech is formed by exciting long and short term filters (124,126) with excitation vectors from a codebook store (114) which is searched by codebook generation (120). A weighting filter (132) is applied to the difference signal a nd the weighted difference is used to calculate an energy measure (134) which is used to control the codebook search (140). The weighting filter is an Rth-order filter controlled with calculated coefficients. The method for calculating coefficients models the frequency respo nse of L Pth-order filters by a single Rth-order filter, where the order R ~ LxP. This method increases the control of a speech coder filter wi thout an increase in hardware complexity.