Patent ID: 7110943

Claim:
An apparatus for performing speech coding in a CELP system, comprising: an adaptive codebook in which previously synthesized execution signals are stored; a stochastic codebook in which a plurality of excitation vectors are stored, said stochastic codebook comprising a first subcodebook in which excitation vectors composed of a small number of pulses are stored and a second subcodebook in which excitation vectors composed of a large number of pulses are stored; a synthesized speech obtainer that obtains synthesized speech using excitation information acquired from said adaptive codebook and said stochastic codebook using linear prediction coefficients obtained by performing linear prediction coefficient analysis on an input speech signal; a gain information obtainer that obtains gain information of said synthesized speech using a relation of said synthesized speech and said input speech signal; and a transmitter that transmits said linear prediction coefficients, said excitation information and said gain information, wherein said stochastic codebook comprises a controller that provides additional gain for respective excitation vector in at least one of said first subcodebook and said second subcodebook according to a distance between pulses of the excitation vectors in said first subcodebook and a computation system that obtains the excitation information using the gain controlled excitation vectors.