A 1.8kbps vocoder based on Mixed Excitation Linear Prediction

With the rapid development of communication technology, there is an urgent need for high quality speech coding algorithm at very low bit rate. In the paper, based on the Mixed Excitation Linear Prediction (MELP) and unequal error channel coding, a low bit rate speech coding algorithm is proposed. According to the different importance for each parameter, the relatively significant code stream information is protected by using channel coding with strong error correcting ability to obtain high-quality synthetic speech at 1.8 kbps with 1/3 redundancy for channel coding. Test results show that the proposed algorithm could provide better speech quality and also has strong robustness for channel error.