A low-delay hybrid vector excitation linear predictive speech coding scheme

The authors study a hybrid approach in determining the excitation vector in a low-delay code excited linear predictive coder. By a judicious division of the composite excitation vector into long-term and short-term components, and the use of switched quantisation, substantial improvement in coding quality is obtained. In addition, the use of an adaptive postfilter which incorporates both the envelope and fine spectral structure of the input signal results in improved recovered speech quality.