Speech coding parameter sequence reconstruction by sequence

Abstract

A method and apparatus which allows the transmission of the perceptually important features of a speech-coding parameter at a low bit rate. The speech coding parameter may, for example, comprise the signal power of the speech. The parameter is processed on a block by block basis. The parameter value at the block boundaries is transmitted by conventional methods such as, for example, by means of differential quantization. The shape of the reconstructed parameter contour within block boundaries is based on a classification. The classification determines perceptually important features of the parameter contour within a block. The classification can be performed either at the transmitting end of the coder (using, for example, the original parameter contour with high time resolution and possibly other speech parameters as well) or at the receiving end of the coder (using, for example, the transmitted parameter values, and possibly other transmitted speech parameters as well). Based on the result of the classification as well as the parameter values at the block boundaries, a parameter contour (within the block) is selected from an inventory of possible parameter contours. The inventory may include a linear interpolation contour and a step function contour. The step function contour may be particularly useful when the features indicate the presence of a plosive. The inventory may adapt to the transmitted parameter values at the block boundaries.