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Efficient pruning algorithm for hidden markov model speech recognition

  • US 4,977,598 A
  • Filed: 04/13/1989
  • Issued: 12/11/1990
  • Est. Priority Date: 04/13/1989
  • Status: Expired due to Term
First Claim
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1. A method for reducing loading of a central processing unit during speech recognition involving hierarchical layers of grammar and wherein models of those hierarchical layers employ a plurality of states including at least a start state and a stop state, only one of said plurality of states at any time being designated the current state, comprising:

  • (a) computing a score for the information-bearing current state;

    (b) comparing said score against a predetermined threshold value to determine whether said information-bearing current state should be retained;

    (c) locating an available slot in a scoring buffer having at least one slot;

    (d) storing information regarding said current state in said available slot;

    (e) setting a scoring buffer slot backpointer;

    (f) assigning a last-time field value in said available slot equal to a current time-index of the central processing unit;

    (g) propagating a time value equal to said current time-index back to all scoring buffer slots along a best path leading to said available slot containing information about said current state;

    (h) parsing a next current state; and

    (i) repeating steps (a) through (h) until all states have been completed.

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