Sound coding device and sound coding method

A one of a single rail/the voice decoder of stereo sound telescopic structure, and one of the stereo sound signal multiple sound rail signal of related small the condition is the efficient device of the code to the stereo sound voice the voice decoder device. The same core layer code part (110), the single a signal generating member (111) from the first ch voice signal and second ch voice signal generating single a signal, a single a signal control part (112) and a to the code of single a signal, a single a signal decoding part (113) is a single track code signal data generating single rail decoded signal outputting the reinforcing layer code part (120). The reinforcing layer code part (120), the first ch prediction signal integrated component (122) is synthesized the first ch prediction signal by the single rail decoded signal and first ch predictive filter quantization parameter; the second ch prediction signal integrated component (126) is synthesized the second ch prediction signal by the single rail decoded signal and second ch predictive filter quantization parameter.