U.S. Philips Corporation

Peter Kroon

Edmond F Deprettere

Robert J Sluyter

A multi-pulse excitation linear-predictive speech coder operates in accordance with an analysis-by-synthesis method for determining the excitation. The coder (10) comprises an LPC-analyzer (11), a multi-phase excitation generator (13), means (12, 14) for forming an error signal representative of the difference between an original speech signal (s(n)) and a synthetic speech signal (s(n)), a filter (15) for perceptually weighting the error signal and means (16) responsive to the weighted error signal (e(n)) for generating pulse parameters controlling the excitation generator (13) so as to minimize a predetermined measure of the weighted error signal. The LPC-parameters and the pulse parameters of the excitation signal (x(n)) are encoded for efficient storage or transmission. The bit capacity required for pulse position encoding of the excitation signal (x(n)) is considerably reduced by arranging the excitation generator (16) for an excitation signal (x(n)) which in each excitation interval (L) consists of a pulse pattern having a grid of a predetermined number (q) of equidstant pulses and by arranging the control means (16) for generating pulse parameters characterizing the grid position (k) relative to the beginning of the excitation interval (L) and the variable amplitudes (b.sub.k (j), 1.ltoreq.j.ltoreq.q) of the pulses of the grid.

Multi-pulse excitation linear-predictive speech coder

A multipulse excitation signal, as a better approximation than a single-pulse excitation signal, searches for a kth pulse which minimizes either a difference between a synthesized and a reference signal, or a distance between a multipulse excitation signal and a residual signal. The search uses an averaging function M.sub.k (n) of a weighted error signal.

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Murray Hill, NJ, United States of America

Peter Kroon