| 摘要 |
PROBLEM TO BE SOLVED: To enable a noise of keeping to be reduced by applying an analogue filter having a constant corresponding to a synchronizing sound in rotation of a blower fan. SOLUTION: This sound suppression device is comprised of means 2 for measuring a noise signal arranged near a blower fan of an indoor device of an air conditioner so as; means 4 for measuring a silencing signal arranged near a silencing speaker; an analogue filter 5 to which a noise signal is inputted; and a silencing speaker 3 to which an output signal of this filter is applied. The filter 5 has a filter constant calculated in such a way that the noise signal with the periodic sound of rotation of the blower fan and the silencing signal will show an inverse phase from each other, the noise from a driving source 1 of the air conditioner is detected by a noise sensing microphone 2, amplified by a next stage amplifier 6 through the analogue filter 5 and then outputted to the silencing speaker 3 as an audio signal. Then, the silencing speaker 3 may generate a controlling sound for suppressing the sound in correspondence with the noise of the noise source. |
