| 摘要 |
PURPOSE:To suppress oscillation, i.e. singing of a loudspeaker system by automatically detecting howling caused in the loudspeaker device and controlling the loudspeaker gain. CONSTITUTION:Among a pair of signals (a) and (b) branched from the signal transmission line by the branching means 1, the signal (b) is delayed 5 to make a certain time difference between both signals. Furthermore, the signal (a) is branched 2 and between a pair of signals branched by phase shifting means 3, 4 and a phase difference of 90 deg. or about 90 deg. is given and then each is multiplied by the other signal branched 1 by the multipliers 6 and 7. The output signals of the multipliers 10 and 11 are integrated at a specified attenuation factor by the integrators 8 and 9. And with the arithmetic units 10 and 11, the absolute value or squared value of the output signal of the integrator is outputted. Then, with the adder 12, the outputs of the arithmetic units are added. By controlling the gain of the gain control circuit Q inserted in the signal transmission line by means of the output signal of the adder 12, the singing generated in the electroacoustic system including the signal transmission line L is suppressed. |
