| 摘要 |
PROBLEM TO BE SOLVED: To prevent deterioration of quality from being accompanied even when the band split number is minimized. SOLUTION: An input signal is band-divided, and with respect to a signal XK(n) every band, a power PX.k (n) is determined (24), whereby a noise average power PavN.k (n) is estimated (51). SNR)k (n) is estimated by the PX.k (n), PavN.k (n) (27), and a gain factor G(SNRk (n)) is determined by SNRk (n) (30). The addition ratioαaccording to the ratio of voice to noise is determined by SNRk (n) so that it is large when S/N is poor, Xk (n) is multiplied by G(SNRk (n)) to provide a signal Pk (n)' reduced in noise (28), Xk (n) is added to Yk (n)' according toαbyαX.k (n)+(1-α)Yk (n)' to provide Yk (n) (53), and all the bands are composed and converted into time area.
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