This paper presents active silencing by hysteresis control method and shows its audible noise reduction effect. A Pentium processor and sound blaster 16 card are used for its implementation. The Sound-Blaster 16 executes the A/D, D/A conversion and is used for operating source of lodspeaker for cancelling. As a result, between the frequency range of 100[Hz] and 200[Hz] there is an audible noise reduction effect from 9[dB] to 15[dB], and between the 300[Hz] and 500[Hz] range there is a reduction from 3[dB] to 5[dB].