What is active noise cancellation and how does it work in headphones?
(Android Central)

Best answer: Active noise cancellation is a process where a microphone is used to detect `noise` and a microprocessor is used to generate a sound that cancels it when played using what's known as destructive interference. It might seem like magic, but the science is simple once you get past the lingo. Amazon: Bose QuietComfort 35 Wireless Headphones ($349) Amazon: Sony WH1000XM3 Wireless Headphones ($348) Audio and science All headphones are `noise canceling` on some level because they block outside sounds by covering your ears. But even the heaviest and tightest pair of headphones can't block all outside noise, such as an airplane engine, so companies like Bose and others have turned to science to tackle the problem. Sound travels in waves, and that's not just a random term applied to them. They have crests and valleys, just like a wave in the ocean, and the larger the distance between the top of a crest and the bottom of a wave (the amplitude) determines the loudness. The distan...