Low bit rate multi-pulse speech coder with natural speech quality

This paper proposes a new low bit-rate speech coding algorithm based on a multi-pulse excitation technique. In the algorithm, an excitation signal in a frame, which includes several pitch periods, is effectively represented by pulses during only one pitch period. Excitation signal for other pitch periods in the frame is reproduced by interpolating the pulses. From several experiments to evaluate the new coder, it is found that the new coder produces natural-sounding speech at low bit rates. Subjective evaluation results show that the new coder at 4.8kb/s attains good speech quality which is almost equivalent to that for 6bit/sample/µ-law PCM.