A wide-band speech coder and a method thereof and a wide-band speech decoder and a method thereof are provided. The wide-band speech coder includes a speech characteristic classification unit, which stipulates a characteristic of speech corresponding to a current frame statistically using an open-circuit
pitch value and a
linear prediction coefficient in which a wide-code speech
signal to be coded is perceptual weigh filtered, an adaptive
codebook retrieving unit, which retrieves a
pitch delay value around the open-circuit
pitch value, calculates a pitch
gain value, generates an adaptive
codebook contribution
signal corresponding to the retrieved pitch
delay value, and outputs a difference between the generated adaptive
codebook contribution
signal and the perceptual weigh filtered signal as a first fixed codebook
target signal, a first fixed codebook retrieving unit, which obtains a first fixed codebook index that can express the first fixed codebook
target signal most properly, and a first fixed codebook
gain value, generates a first fixed codebook contribution signal corresponding to the retrieved index, and outputs a difference between the first generated fixed codebook contribution signal and the first fixed codebook
target signal as a second fixed codebook target signal, a second fixed codebook retrieving unit, which includes at least two second fixed codebooks according to a speech characteristic, selects a second fixed codebook according to the speech characteristic, and retrieves second fixed codebook indices that can express the second fixed codebook target signal most properly, and second fixed codebook
gain values, and a parameter
multiplexer, which quantizes and multiplexes the speech characteristic information, the pitch
delay value, the pitch gain value, the first fixed codebook index, the first fixed codebook gain value, the second fixed codebook indices, and the second fixed codebook gain values, makes them as a bit
stream, and transmits the bit
stream to an external speech decoding terminal.