| 摘要 |
PROBLEM TO BE SOLVED: To keep characteristics almost at a soundless level excellent without increasing the scale of a processing circuit. SOLUTION: A high-frequency coefficient calculating circuit 1 calculates a mute coefficient of a section between a specified threshold and a mute coefficient corresponding to a maximum audio level obtained by increasing the level of an audio signal most, increases or decreases the mute coefficient by using a specified difference value, and calculates a new mute coefficient. Further, a low-frequency coefficient calculating means 2 calculates a mute coefficient of a section between the specified threshold and a mute coefficient corresponding to a minimum audio level obtained by attenuating the level of the audio signal most and increases or decreases the mute coefficient by using a second difference value which is smaller than the specified difference value used by the high-frequency coefficient calculating means 1, and calculates a new mute coefficient. A selection means 3 compares the mute coefficient with a specified threshold and selects the high-frequency coefficient calculating means 1 or low-frequency coefficient calculating means according to the comparison result. COPYRIGHT: (C)2004,JPO&NCIPI
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