| 摘要 |
PURPOSE:To stop howling by delaying a signal on a signal transmission line by a time of a half wavelength of a howling frequency when howling takes place so as to interfere the phase condition of positive feedback causing howling. CONSTITUTION:When howling takes place at a frequency, it is detected by a detection means 10 and the delay time of a delay means 5 is set to a time by a half wavelength of a howling frequency to be detected. Thus, the phase condition of positive feedback is not established at a frequency causing howling. Then the signal component of the howling frequency fed back from a microphone 1 is made opposite in phase to the phase of a substantial signal thereby stopping howling. |
