How do noise-cancelling headphones work?

Asked by: Anonymous
Noise cancelling works by generating a waveform that’s an upside down version of the original. Put the two together and they both disappear. But things get complicated when the original noise source is dispersed and allowed to bounce off objects and surfaces. Noise-cancelling headphones work because they just have to operate in that small space around your ears. Sadly, we don’t have the technology to do it for a whole room yet.

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