Patent ID: 6973424

Claim:
A speech coder comprising: a spectral parameter calculating unit supplied with a speech signal for calculating and quantizing spectral parameters; an adaptive codebook unit for calculating a delay and a gain from a preceding quantized excitation signal by the use of an adaptive codebook, predicting the speech signal, and calculating a residue; and an excitation quantizing unit for quantizing an excitation signal of said speech signal by the use of said spectral parameters to produce an output; said speech coder further comprising: a judging unit for extracting a feature from said speech signal to judge a mode; a codebook for representing the excitation signal by a combination of a plurality of nonzero pulses and simultaneously quantizing amplitudes or polarities of said pulses in case where the output of said judging unit is a predetermined mode; said excitation quantizing unit for searching combinations of code vectors stored in said codebook and a plurality of shift amounts for shifting pulse positions of said pulses and producing as an output a combination of the code vector and the shift amount, the produced combination minimizing distortion from an input speech; and a multiplexer unit for producing a combination of the output of said spectral parameter calculating unit, the output of said judging unit, the output of said adaptive codebook unit, and the output of said excitation quantizing unit.