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A speech detector uses a signal classifier (19) to identify portions of a representation of the average magnitude of a group of signal samples indicative of either speech or noise. A controller (33) in the signal classifier follows a four state sequence using appropriate time constants for signal me

A speech detector uses a signal classifier (19) to identify portions of a representation of the average magnitude of a group of signal samples indicative of either speech or noise. A controller (33) in the signal classifier follows a four state sequence using appropriate time constants for signal measures in a variety of signal conditions in defining the speech and noise portions of the representation. A level estimator (21) uses selectively obtained signal measures from the defined portions of the representation to provide adaptively variable decision levels. A speech definer (16) compares the representation to a first decision level and the signal samples to a higher decision level to indicate the occurrence of speech signal activity when either decision level is exceeded. In a two way transmission arrangement, a receive trunk speech detector uses a stretcher (133) to prevent adaptation of the transmit speech detector thresholds when echo signals are present.

대표청구항 ▼

Apparatus for indicating the occurrence of speech in a signal indicative of both speech and noise, the apparatus including: means for generating (13) a representation of the average magnitude of the signal during a moving time interval; the apparatus being characterized by classifying means (19) for

Apparatus for indicating the occurrence of speech in a signal indicative of both speech and noise, the apparatus including: means for generating (13) a representation of the average magnitude of the signal during a moving time interval; the apparatus being characterized by classifying means (19) for receiving said representation and a noise level estimate, said classifying means generating a first output to indicate when said representation has prescribed attributes indicative of speech and a second output to indicate when said representation has prescribed attributes indicative of noise; level estimator means (21) responsive to said first and second outputs and said representation, said level estimator means providing a noise level estimate using the portion of said representation identified by the occurrence of said second output, said level estimator means providing a first decision level output by combining said noise level estimate and the portion of said representation defined by the occurrence of said first output in excess of a prescribed amount of said first decision level output; and comparing means (16) for providing an output indicative of the occurrence of speech signal activity when said first decision level is exceeded by the signal.