| 摘要 |
PURPOSE:To increase maximum sound volume which can be outputted without the occurrence of howling by giving generous phase fluctuation to a sound wave which is given from a speaker when a signal including an element growing as the howling is detected. CONSTITUTION:A timer circuit 10 sends the signal of high level continuing long time to a switch circuit 7 every time a wave high value comparison circuit 9 rises from a low level to a high level and a phase fluctuation circuit 5 gives the phase fluctuation to a passing sound signal by synchronizing with the output of a triangular wave oscillation circuit 6. That means, by comparing the wave high value of the two continuous positive and negative electrodes of the sound signal, the generous phase fluctuation is given to frequency extending wide band at the same time only when the signal including the element growing to the howling among the sound signals is recognized. Thus the oscillation of the specified frequency can be quickly and surely restrained and simultaneously to that, the deterioration of sound quality caused by adding the phase fluctuation to the sound signal can be stopped at the minimum. |
