| 摘要 |
PROBLEM TO BE SOLVED: To obtain a noise restricting effect with high precision by reducing a spectrum residual. SOLUTION: Noise spectrums of each frame from a first frame to a T-th frame are obtained in a step S1. Then an average spectrum N and a standard deviation V are obtained in the noise in a step S3. In a step S4, a noise restriction amount D(ω, t) is calculated concerning each frequencyωby defining a present frame as the t-th frame (t>T). In this case, the noise restriction amount D(ω, t) is calculated based on a present input spectrum X(t), and the average value N and the standard deviation V of the noise. In a step S5, a voice spectrum is estimated through the use of S(t)=X(t)-D(t). The noise restriction amount D(ω, t) is calculated based on not only the present input spectrum X(t) and the noise average value N but the noise standard deviation (the square root of a variance) V. Thus, the restriction amount D(ω, t) is made to correspond further to an actual environmental noise, so that the spectrum residual is sufficiently reduced. COPYRIGHT: (C)2004,JPO
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