see people with them, and what happens here is it's supposed to be those noise cancellation headphones. All they do is they take in the ambient noise that's around it, and there's actually battery in the headphones, that then produces waves that are going to destructively interfere with that ambient noise.

我从来没有用过这个,但你会看到有人带他们,它们可以作为消噪音耳机,它们所做的就是采入,周围的随机噪声，耳机里面是，有电池的，然后它能产生和,随机噪声相干相消的声波。

麻省理工公开课 - 化学原理课程节选

And the fact that we're always facing some risk of death recedes into the background in the way that most of us don't hear background noise-- that what jumping out of an airplane does for you is it spikes the risk of death.

我们一直面对的某些死亡的风险,这种情况下变成了背景声音,因为我们大部分人都听不到背景的噪声-,而跳下飞机带给你的,是死亡的风险上升。

耶鲁公开课 - 死亡课程节选