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Wordspotting for voice editing and indexing

  • US 5,199,077 A
  • Filed: 09/19/1991
  • Issued: 03/30/1993
  • Est. Priority Date: 09/19/1991
  • Status: Expired due to Fees
First Claim
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1. A wordspotting method for determining the location of a word in recorded continuous voice-speech using a single spoken version of the word as a keyword, comprising:

  • (a) creating a first hidden Markov model (HMM) representing features of the voice that recorded the speech,(b) providing the keyword,(c) creating a second hidden Markov model (HMM) representing features of the keyword to be spotted, said first and second HMMs comprising a sequence of states each having an output representative of an acoustic unit and transition probabilities to succeeding states and having a normalized forward probability for each state and having an endstate for the keyword,(d) using the first and second HMMs, scanning through the recorded speech computing the normalized forward probability for each state searching for a peak in the a posteriori probability of the endstate of the keyword thus hypothesizing that the end time of a keyword has been found,(e) if a peak is found in step (d), stopping the scanning and backtracking through the recorded speech to the most probable hypothesized keyword beginning time while computing a score for that hypothesized keyword, where the score represents a measure of how well the second HMM representing background speech fits the hypothesized keyword beginning and end times relative to how well the first HMM fits the said beginning and end times,(f) indicating the keyword has been spotted in the recorded speech when the score computed in step (e) exceeds a pre-set value.

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