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Synthesis of speech signals in the absence of coded parameters

  • US 6,014,621 A
  • Filed: 04/02/1997
  • Issued: 01/11/2000
  • Est. Priority Date: 09/19/1995
  • Status: Expired due to Term
First Claim
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1. A method of generating coefficient signals representing frequency components of a signal representing speech information based on an estimate of the signal spectrum and a noise masking measure associated with the speech signal, the method comprising:

  • generating a first signal relating the estimate of the signal spectrum to the noise masking measure at each of one or more frequencies;

    for one or more of said frequencies, forming a coefficient signal magnitude based on said first signal at a corresponding frequency, andselecting a coefficient phase at random, wherein the step of forming a coefficient signal magnitude comprises forming the magnitude as a function of a quantized gain signal associated with the frequency corresponding to said coefficient, wherein the first signal relating the estimate of the signal spectrum to the noise masking measure at each of one or more frequencies comprises a ratio of the estimate of the signal spectrum to a perceptual threshold signal, and wherein when said ratio is greater than a predetermined threshold, the magnitude of said coefficients is at least a predetermined amount above said gain signal evaluated at said frequency.

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