本题目来源于试卷: gc textbook chapter 12 Sound，类别为 通用国际物理
[问答题]
Traditional methods of protecting the hearing)8zvcw8gd) l ,qz 3sl.dr/bnr of people who work in ar u/b8sbgzl t lus5bf:y. 03n j2kmx2j)eas with very high noise levels have consisted mainly of efforts to block or reduce noise levels. With a relatively new technology, headphones are worn that do not block the ambient noise. Instead, a device is used which detects the noise, inverts it electronically, then feeds it g/2j 3lbuf :tbsm8bujl0kxyn.5)2sz to the headphones in addition to the ambient noise. How could adding more noise reduce the sound levels reaching the ears?
参考答案:
So-called active
noise reduction devices work on the principle of interference. If the electronics are fast enough to detect
the noise, invert it, and create the opposite wave (180 $^{\circ} $ out of phase with the original) in
significantly less time than one period of the components of the noise, then
the original noise and the created noise will be approximately in a destructive
interference relationship. The person
wearing the headphones will hear a net sound signal that is very low in intensity.
本题详细解析:
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