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Utterance verification using word based minimum verification error training for recognizing a keyboard string

  • US 5,717,826 A
  • Filed: 08/11/1995
  • Issued: 02/10/1998
  • Est. Priority Date: 08/11/1995
  • Status: Expired due to Term
First Claim
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1. A method for use in a speech recognition system to verify whether input speech signals comprising digitized speech represents a probable keyword, said probable keyword being determined by a speech recognizer, said method comprising the steps of:

  • processing said digitized speech into recognizer observation vectors;

    processing said recognizer observation vectors in a Hidden Markov Model (HMM) keyword recognizer, said HMM keyword recognizer having output signals representing said probable keyword and a likelihood score for said word;

    developing a plurality of at least three verification scores for said probable keyword;

    developing a keyword verification confidence score by combining said plurality of word verification scores into word likelihood ratio for said keyword;

    verifying whether said probable keyword is present in said input speech signals by comparing said keyword verification confidence score to a threshold; and

    delivering as an output said probable keyword if said threshold test is met, and delivering as an output an indication that no keyword is detected if said threshold test is not met.

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