| 摘要 |
PROBLEM TO BE SOLVED: To provide a silencer capable of canceling random noises even when a general-use canceling speaker without excellent delay characteristic is adopted. SOLUTION: Noise from a noise source 1 typically shown by an air conditioner is detected by a microphone 2 for noise detection, and a proper filter constant corresponding to noise signal of the current noise is source is selected from a table in a storage part, and the noise outputted to a canceling loudspeaker 3 arranged forward to a testee by a distance 1 from the noise source 1 though a filter 5 changed in the characteristic by setting the constant and through the next stage amplifier 6. Otherwise, through a proper filter 5 selected from a plurality of filters comprising filter constants correspondingly to noise signal of the current noise source and through the next stage amplifier 6, the noise is outputted to a canceling loudspeaker 3 arranged forward to a testee by a distance 1 from the noise source 1. And, even if an ordinary loudspeaker without an ideal delay characteristic is used, a delay in a phase characteristic of the loudspeaker is compensated to a large extent in high a frequency range, therefore, a satisfactory muffling effect comes into play. |
