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High-accuracy, low-distortion time-frequency analysis of signals using rotated-window spectrograms

  • US 5,845,241 A
  • Filed: 09/04/1996
  • Issued: 12/01/1998
  • Est. Priority Date: 09/04/1996
  • Status: Expired due to Term
First Claim
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1. A speech recognition apparatus, comprising:

  • a spectral shaping source for generating a plurality of digital signal samples representative of an input speech signal;

    a signal processor coupled to said source, comprising;

    means for transforming said plurality of said signal samples to pre-processed signals representative of the frequency domain at various angular orientations;

    means for generating initial time-frequency distributions of said pre-processed signals using analysis windows; and

    means for rotating said time-frequency distributions back by said various angular orientations for generating a plurality of rotated window spectrograms, andsignal modeling apparatus for comparing the plurality of rotated window spectrograms against each of a plurality of word models and identifying the closest match.

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