A 1200 bps speech coder with LSF matrix quantization

Abstract

A new 1200 bps speech coder designed with a tree searched multistage matrix quantization scheme is proposed. To improve speech quality and reduce the average bit rate, we have developed a new residual multistage matrix quantization method with the joint design technique. The new,joint design algorithm reduces the codebook training complexity. Other new techniques for improving the performance include joint quantization of pitch and voiced/unvoiced/mixed decisions and gain interpolation. For the new matrix quantization based speech coder (MQBC), the listening tests have proven that an efficient and high quality coding has been achieved at bit rate 1200 bps. Test results are compared with the 2400 bps LPC10e coder and the new 2400 bps MELP coder which has been chosen as the new 2400 bps Federal Standard.