| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce noise of low frequency sound regardless of a kind and shape of a noise source.SOLUTION: A flexible duct 22 introduces noise output from a noise source to an intermediate part among plural speakers 16 of a speaker unit 17. An error microphone 18 collects noise on an opposite side of the noise source from the speaker unit 17, and outputs an acoustic signal corresponding to the collected noise. A noise reduction device 20 creates a reduction signal for reducing noise on the opposite side of the noise source from the speaker unit 17, based on the acoustic signal. Then, the plural speakers 16 of the speaker unit 17 radiates control sound, and at the time, the control sound radiated from the plural speakers 16 reduces the noise.</p> |
