| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a signal processing device which suppresses an occurrence of an abnormal noise by return noise. Ž<P>SOLUTION: A signal processing apparatus includes a band division circuit Fd generating a plurality of subband signals by performing a first orthogonal transform to a digital voice input signal, a plurality of AGC amplifying circuits G1-Gn provided corresponding to each of signal groups S1-Sn composed of at least three subband signals whose frequency bands are adjoining with each other, obtaining a signal group level based on a level of the subband signal except the subband signals whose frequency bands are adjoining to other signal groups in each corresponding signal group, determining a gain based on the signal group level, and performing amplifying processing to all of the subband signals within the corresponding signal group based on the gain, and a band synthetic circuit Fc performing an inverse transform of the first orthogonal transform to a signal to which the amplifying processing is performed by each of the AGC amplifying circuits G1-Gn and outputting the digital voice output signal. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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