MULTIPLE VARIABLE THRESHOLD SPEECH DETECTOR

摘要

MAY, C. J. JR. 16 MULTIPLE VARIABLE THRESHOLD SPEECH DETECTOR A speech detector uses a signal classifier to identify portions of a representation of the average magnitude of a group of signal samples indicative of either speech or noise. A controller 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 to provide adaptively variable decision levels. A speech definer 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 to prevent adaption of the transmit speech detector thresholds when echo signals are present.