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Automatic gain control in a speech recognition system

  • US 6,314,396 B1
  • Filed: 11/06/1998
  • Issued: 11/06/2001
  • Est. Priority Date: 11/06/1998
  • Status: Expired due to Term
First Claim
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1. A speech recognition preprocessor, comprising:

  • an analyzer for receiving a digital speech signal generating therefrom a sequence of frames, each frame having a plurality of samples from said digital speech signal;

    means coupled to said analyzer means for tracking an upper energy envelope, an average energy envelope, and a lower energy envelope by a plurality of energy tracks in one or more consecutive frames of said digital speech signal, wherein said energy tracks are based on a high biased running mean, a low biased running mean and a nominally unbiased running mean; and

    means coupled to said tracking means for computing a normalized energy value and providing said normalized energy value to a speech recognition system.

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