How do noise reduction headphones work?

Answer by  pqman17 (72)

Noise reduction headphones work by simply insulating your ear from background noise, while canceling use a microphone to take in background noise and filter it out by inverting the signal.

Answer by  thorsdecree (409)

Active noise reduction microphones create sound waves that are out of phase with ambient noise, thus canceling both the ambient noise and the cancellation waves created by the headphones. Passive NC headphones use padding and an airtight seal around the ears to absorb ambient noise into the padding.