Low-rate CELP speech coding using an improved weighting function

Below 4.8 kbits/s, code-excited linear prediction (CELP) coders in general suffer from two kinds of perceptually important degradation. They are inter-harmonic noise and high frequency mismatch. To remedy these degradations, we propose in this paper an improved weighting function which utilizes the spectral weighting methodology and also takes into account the periodic character in voiced sound. The function can adapt to variation of pitch by itself without any pitch estimation in voiced sound and is also applicable to all speech segments without any voiced/unvoiced discrimination algorithm. Simulation results show that the performance of the CELP coder with the proposed weighting function is better than that of the conventional CELP coder