| Speech coding technology make up a large proportion in communication system. With the development of the society, the speech coding technology request higher and higher. So it is necessary for speech coder with lower coding rate and higher speech quality. However, speech quality and coding rate is contradictory. Code-excited linear prediction (CELP) coding technology is a mainstream coding technology for its performance.This paper focus on improving speech quality, and research4.8KB/s code-excited linear prediction coding technology. In order to improve the quality of speech coding, this paper main focus on the speech linear prediction analysis technique, perceptually linear prediction and RASTA filter. Putting forward a RASTA-PLP-CELP coding model by using PLP analysis instead of linear prediction analysis. This model is simulated by matlab. The results show that the proposed coding model have a better speech quality than conventional one under nosiy environment, and at the same time, have the same coding rate. |
