Voice activity detection process and means for implementing said process

  • US 4,672,669 A
  • Filed: 05/31/1984
  • Issued: 06/09/1987
  • Est. Priority Date: 06/07/1983
  • Status: Expired due to Term
First Claim
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1. In a system wherein at least one voice signal provided by a source via an input channel is coded to derive therefrom blocks of samples x.sub.(n) of predetermined duration, and, short term power spectrum information, a voice activity detection process for discriminating active voice blocks from non active voice blocks said process including, for each block of samples the following steps:

  • (a) Setting an amplitude threshold VADTH;

    (b) Processing the block of x.sub.(n) values to derive therefrom a signal energy representative information XM ;

    (c) First comparing XM to VADTH and adjusting said threshold accordingly;

    (d) Second comparing XM to k. VADTH, where k is a predetermined numerical value and VADTH is the adjusted threshold, to derive therefrom a channel activity indication when XM is larger than k. VADTH, or an ambiguity indication otherwise, whereby a hangover timer is set upon activity detection or ambiguity resolution operations are to be performed upon ambiguity detection, which ambiguity resolution includes;

    decreasing and testing said timer contents whereby a positive timer contents is indicative of an active voice block and a negative timer contents is still indicative of an ambiguity situation;

    computing short term power spectrum information variation between the currently processed block and at least one previously processed block ; and

    ,comparing said short term power spectrum variation with a preset reference level, whereby the currently processed ambiguous block is considered inactive or active based on said comparison indication.

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