Time encoding of LPC roots

A time encoding scheme of the center frequencies of the LPC inverse filter roots is presented. The roots are represented in terms of center frequency (CF) and bandwidth (BW), and the continuity of the CF´s in time is established by a dynamic programming scheme which has a cost function depending on both CFs and BWs. Segmentation points are set at the beginning or end of root tracks, at the voiced-unvoiced transitions and at the peaks of a function measuring the dissimilarity of adjacent frames. The tracks within segments are then fitted by linear combinations of orthogonal polynomials. Without quantization, the processed speech is subjectively indistinguishable from the original synthetic speech. Good quality is achieved even below 1000 bps.