A Computationally Efficient CELP Codec with Stochastic Vectorquantisation of LPC Parameters

In this contribution, computationally efficient CELP structures are proposed for low-complexity speech coding below 6.4Kbits/s. We also report on a new approach for low bit rate speech coding using binary excitation pulses, which delivers the quality of the CELP codec without the excitation codebook storage, and with a very simple excitation determination procedure. Furthermore, we propose a switched-adaptive stochastic vector quantisation scheme for quantising the line spectrum frequencies using 22 bits without any perceivable spectral distortion.