Patent ID: 8200483

Claim:
An adaptive excitation vector quantization apparatus that is used in code excited linear prediction speech encoding to generate linear prediction residual vectors of a length m and linear prediction coefficients by dividing a frame of a length n into a plurality of subframes of the length m and performing a linear prediction analysis, (the length n and the length m being integers, the length n being a multiple of the length m, the apparatus comprising: an adaptive excitation vector generator including at least one of at least one processor and at least one circuit that cuts out an adaptive excitation vector of the length n from an adaptive excitation codebook; a target vector generator including at least one of the at least one processor and the at least one circuit that forms a target vector of the length n by adding the linear prediction residual vectors of the plurality of subframes; a synthesis filter including at least one of the at least one processor and the at least one circuit that generates m×m impulse response matrixes using the linear prediction coefficients of the plurality of subframes; an impulse response matrix former including at least one of the at least one processor and the at least one circuit that forms a n×n impulse response matrix using the m×m impulse response matrixes; an evaluation measure calculator including at least one of the at least one processor and the at least one circuit that calculates an evaluation measure of an adaptive excitation vector quantization per each pitch period candidate, using the adaptive excitation vector of the length n, the target vector of the length n and the n×n impulse response matrix; and an evaluation measure comparator including at least one of the at least one processor and the at least one circuit that compares the evaluation measure with respect to each pitch period candidate and calculates a pitch period of a highest evaluation measure as a quantization result.