Patent ID: 7203641

Claim:
A speech encoding method of encoding an input speech for each of given length sections which are called frames, comprising: a fixed excitation generating step of generating a plurality of fixed excitations; a first distortion calculating step of calculating a distortion related to a waveform defined between a signal to be encoded which is obtained from the input speech and a synthetic vector which is obtained from the fixed excitation as a first distortion for each of the fixed excitations; a second distortion calculating step of calculating a second distortion different from the first distortion which is defined between the signal to be encoded and the synthetic vector which is obtained from the fixed excitation for each of the fixed excitations; an evaluation value calculating step of calculating a given evaluation value for a search by using the first distortion and the second distortion for each of the fixed excitations; and a searching step of selecting the fixed excitation that minimizes the evaluation value for the search and outputting a code which is associated with the selected fixed excitation in advance.