PROCESS FOR THE VECTOR QUANTIZATION OF LOW BIT RATE VOCODERS

A process for the vector quantization of low bit rate vocoders, including determining a coding region by surrounding with an envelope a scatter of points of an autocorrelation matrix of reflection coefficients of a filter configured to model a vocal tract, wherein the envelope has a shape selected from the group consisting of a hyperellipsoid shape and a pyramidal shape, the envelope being centered at the barycenter of the scatter of points; determining principal axes of the volume of points inside the envelope; projecting area coefficients of the autocorrelation matrix onto the principal axes; partitioning the interior volume of the envelope into elementary volumes; and coding partition coefficients resulting from partitioning the interior volume on the basis of coordinates of said partition coefficients in a space defined by the principal axes of the volume of the points inside the envelope, while allocating as code values only values corresponding to locations of the elementary volumes in which said partition coefficients lie.