Very low delay and high quality coding of 20 Hz-15 kHz speech signals at 64 Kbit/s

An algorithm for coding 20 Hz-15 kHz speech signals at 64 kbit/s with a very low delay (frame of 0.16 ms) is presented. To achieve a quality near to transparency, the authors propose adapting the Low-Delay CELP coder to the 15 kHz bandwidth and suggest a new noise shaping method based on a psychoacoustic model. In this way they take advantage of linear predictive coding and masking properties of the human perception system. Finally, an algebraic codebook is proposed, allowing an important reduction of coder computational complexity, without decreasing the perceived quality of signals.