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Speech recognition method having noise immunity

  • US 4,713,777 A
  • Filed: 05/27/1984
  • Issued: 12/15/1987
  • Est. Priority Date: 05/27/1984
  • Status: Expired due to Term
First Claim
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1. In a speech recognition apparatus wherein speech units are each characterized by a sequence of template patterns, and havingmeans for processing a speech input signal for repetitively deriving therefrom, at a frame repetition rate, a plurality of speech recognition acoustic parameters, andmeans responsive to said acoustic parametersfor generating likelihood costs between said acoustic parameters and said speech template patterns, andfor processing said likelihood costs for determining the speech units in said speech input signal,a method for inhibiting a response to nonvocabulary utterances in a speech input for which template patterns have not been created, comprising the steps ofrepeatedly, at a frame repetition rate, generating acoustic parameters representing said speech input,generating likelihood costs at each frame time for said acoustic parameters and said template patterns, said template patterns including a pattern representing silence,beginning a normal speech recognition process whenever said cost for an active template pattern is better than a predetermined threshold value, andreverting to a non-speech recognition process whenever said cost of said template patterns, including silence, is worse than said predetermined threshold value.

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