Electrical audio signal processing systems and devices – One-way audio signal program distribution – Public address system
Patent
1989-02-15
1990-10-16
Harkcom, Gary V.
Electrical audio signal processing systems and devices
One-way audio signal program distribution
Public address system
G10L 908
Patent
active
049641697
ABSTRACT:
A low bit rate speech coding method and implementing apparatus in which a linear predictive coding (LPC) speech synthesizer receives an excitation sequence comprised of pulses having selected amplitudes at predetermined positions within a frame to minimize the weighted mean square error between the synthetic speech produced by the LPC synthesizer and the input speech. Pulse locations and the pulse amplitudes at the respective locations are determined by a sequential processing technique in which the amplitude and location of each pulse are determined in accordance with the previously determined amplitudes and locations of the pulses preceeding the present pulse in the same frame; and specifically by determining the amplitude g.sub.k and location l.sub.k of a new pulse in a frame from selected pulses S at locations k-1 through k-S close to location l.sub.k. The number S of preceeding pulses used to determine the pulse at location l.sub.k is selected such that the distance between the Sth pulse preceeding the pulse at location l.sub.k affects the determination of the pulse at l.sub.k while pulses prior to the Sth pulse have no appreciable effect on the determination of the pulse at l.sub.k. That is, each of the S pulses within a threshold distance T.sub.th is judged to effect the detection of the pulse at l.sub.k while pulses preceeding the pulse at l.sub.k and outside of the range T.sub.th are judged to not effect the determination of the pulse at l.sub.k.
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"Digital Proceedings of Speech Signals", by L. R. Rabiner and R. W. Schafer, Prentice-Hall Signal Processing Series, pp. 396-407, 1978.
Harkcom Gary V.
Knepper David D.
NEC Corporation
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