| 摘要 |
<p>PURPOSE:To prevent howling, by dividing the sound input signal frequency by filters and by mixing outputs of respective filters after making the output signal of the low-pass filter zero-level if this output signal is a single frequency. CONSTITUTION:The sound output signal is input to high-pass filter 6 and low-pass filter 7 and outputs of them are mixed by mixing amplifier 8. Single frequency (f) which passes through low-pass filter 7 is supplied to mixing amplifier 11 by delaying the output waveform of sound delay circuit 10 by the half period for the output waveform of noninversion amplifier 9, and the output level is made zero to cancel input frequency (f).</p> |
