system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Noise cancelling headphones: how can sounds waves disable other sound waves? Is it possible that before the external sound wave travels the space between my headphones’ external microphone and my ear, my device has enough time to produce a sound wave that perfectly cancels it out?
gpt
Sound is pressure waves. And when one sound wave creates low pressure and another creates high pressure they end up canceling each other out in that perticular spot where they cross. The noise cancelling headphones just make sure that the spot where these waves cancel is right at the entrence of your ear canal. They are able to do this because the microphones are much farther away from your ear then the speakers and electricity travels almost instantanious while the speed of sound is much slower. The headphones may still employ techniques to predict the noises before they happen by analyzing the frequency and the rhythm of the various noises it picks up.