U.S. Philips Corporation

Robert J Sluyter

Leonardus F Willems

Peter Kroon

Edmond F Deprettere

Hendrikus Duifhuis

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

Method of and arrangement for the determination of the pitch of speech signals in a system of speech analysis, wherein sequences of significant peak positions of the amplitude spectrum of a speech signal are derived (13) from time segments of the speech signal by means of a discrete Fourier transform (12). In order to reduce the influence of noise signals and noise components, respectively, in the amplitude spectrum the significant peak positions are compared with different masks (15), which have apertures at harmonic distances of the associated fundamental tone. The mask which matches the sequence of significant peak positions best is selected (20). A probable value for the pitch is now computed with the harmonic numbers now known of the significant peak positions which are located in apertures of the selected mask. The mean square error between these significant peak positions and the corresponding harmonics of the finished tone can be used as a criterion (21).

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Eindhoven, Netherlands

Robert J Sluyter