| 摘要 |
PURPOSE:To improve the quality of amplified sound by making an automatic gain control function effective while a voice detection signal continuous and decreasing the gain of an amplifier to a prescribed value for a prescribed time at the end of the effective state. CONSTITUTION:A continuous voice detector 20 counts a frame number where the on-state of a voice detection signal 2 continues, a signal line 21 is made live while the on-state continues to make the AGC of the amplifier 22 effective. A hang-over adaptor 23 turns always off a signal 24 controlling a selector 25, the change from ON to OFF of the line 21 is detected and a line 24 is turned on for several frames. The selector 25 inputs a prescribed value (d) to an adder 26 when the line 24 is turned on and inputs 0 to the adder 26 when the line is in off-state. Thus, after the line 21 of the detector 20 changes from ON to OFF, the gai of the amplifier 22 is lowered by (d) for a period of several frames. Since malfunction of the voice amplifier AGC due to noise of no voice period s prevented, the quality of the amplified voice is improved. |
