A method and apparatus for reducing the complexity of linear prediction
analysis-by-synthesis (LPAS) speech coders. The speech coder includes a
multi-tap pitch predictor having various parameters and utilizing an
adaptive codebook subdivided into at least a first vector codebook and a
second vector codebook. The pitch predictor removes certain redundancies
in a subject speech signal and vector quantizes the pitch predictor
parameters. Further included is a source excitation (fixed) codebook that
indicates pulses in the subject speech signal by deriving corresponding
vector values. Serial optimization of the adaptive codebook first and then
the fixed codebook produces a low complexity LPAS speech coder of the
present invention.
