| 摘要 |
PURPOSE:To adjust a sound volume without spoiling characteristics, such as frequency characteristic, dynamic range, distortion rate, SN ratio, etc., by changing a deglitching pulse width by means of a digital signal and utilizing a holding effect. CONSTITUTION:Digital acoustic signals a' are over-sampled to (n) times by an interpolation type digital filter 9 and converted into analog signals c' by a DA converter 10. On the other hand, digital control signals h' inputted from a control signal input terminal 14 become deglitching pulses f' having a width (tau) at a deglitching pulse width controlling circuit 15 and inputted to a deglitching circuit 11. When the width (tau) of the deglitching pulses f' is controlled, a holding effect is obtained and the output analog level can be changed. Therefore, the necessity of a voltage controlling amplifier, etc., after a low-pass filter 12 can be eliminated and, since signals which are over-sampled to (n) times are handled, sound volume adjustment by digital signals can be performed without deteriorating various kinds of characteristics of acoustic signals.
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