Patent ID: 7502735

Claim:
A speech signal transmission apparatus that multiplexes and packetizes first coded information coded in a normal state and second coded information used for improving quality of decoded speech when a frame loss occurs, and sends the packetized information, the speech signal transmission apparatus comprising: a CELP excitation generating section that comprises an adaptive codebook and a fixed codebook; a first error calculating section that calculates a first error signal between a target signal and a synthesized signal generated by the adaptive codebook; a second error calculating section that calculates a second error signal between the target signal and a synthesized signal generated by the fixed codebook; an error signal ratio calculating section that calculates the ratio of the first error signal to the second error signal; a speech frame classifying section that classifies a speech frame according to the magnitude of the ratio; and a decision section that decides whether or not to multiplex the second coded information based on the classification result of the speech frame classifying section.