1976-08-17
1977-06-07
Claffy, Kathleen H.
H04J 600
Patent
active
040284964
ABSTRACT:
The detection sensitivity and noise rejection of an arrangement for detecting speech in the presence of noise is improved by accumulating the weighted differences between input signal samples and their short-term running average. The detector thus tracks ambient noise, providing an adaptive detection threshold such that detection sensitivity is increased in low noise environments without excessive false operation on high level noise. The peak average attained during an interval of speech is used to provide variable hangover upon cessation of speech, yielding greater hangover for weak talkers than for loud talkers. In an illustrative embodiment of the speech detector used in a speech interpolation system, protection is afforded also against false transmission path operation due to detection of speech echo.
REFERENCES:
patent: 3520999 (1970-07-01), May
patent: 3644680 (1972-02-01), Amano
patent: 3649766 (1972-03-01), LaMarche
patent: 3712959 (1973-01-01), Fariello
patent: 3801747 (1974-04-01), Queffeulou
patent: 3832493 (1974-08-01), Clark
E. Lyghounis, et al., "Speech Interpolation in Digital Transmission Systems", IEEE Trans., v.COM-22, No. 9, Sept. 1974, p. 1179ff.
J. A. Jankowski, Jr., "A new digital voice-activated switch", Comsat Technical Review vol. 6, No. 1, Spring 1976, p. 159ff.
A. M. Molinari et al., "Bit Rate Per Channel Halving in PCM Multiplexes . . .", Zurich Seminar on Digital Comm., 1976, pp. A7.1-A7.8.
LaMarche Robert Ernest
May, Jr. Carl Jerome
Zebo Timothy James
Bell Telephone Laboratories Incorporated
Chayt Kenneth A.
Claffy Kathleen H.
Snedeker D. E.
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