A new fast pitch search algorithm using the abbreviated correlation function in CELP vocoder

To find the optimum pitch lag in a CELP vocoder with reduced computation requirement, a new pitch search algorithm is proposed. This algorithm is based on the sign of the abbreviated correlation function and agrees with that of the original correlation function. The abbreviated correlation function makes it possible to confine the candidates for the optimum pitch to the positively correlated lags, which reduces the computation load considerably. However, since the optimum pitch can be found without omission, the degradation of segmental SNR (SEGSNR) does not occur with the proposed algorithm. Experimental results show that the proposed algorithm can achieve 40% of computation time reduction compared to the conventional full search method.