Enhancement of Voice Quality and Bit-rate Reduction by Prosodic Control in G.723.1 Vocoder

摘要

Speech coding techniques have been studied not only to reduce the complexity and bit rate but also to improve the sound quality.CELP type vocoder,used as standard,supports the great sound quality even low bit rate.In this paper,the preprocessing of input speech to reduce the bit rate is different from the conventional vocoder.Different kinds of parameter are used for the preprocessing compared with the other parameters to find the more appropriate parameter for the vocoder.The parameters are used to synthesize the speech not to encode or decode for coding technique so we proposed the simple algorithm not to have the influence on the processing time or the computation time.The parameters in the preprocessing step are speaking rate,duration,and PSOLA technique.