How does noise-cancelling technology actually work?

Noise-cancelling headphones make loud sounds quiet by using special speakers inside your ears.

Imagine you're playing with a toy that makes a buzzing sound, and it's really annoying. Now imagine someone else is also making the same buzzing sound right next to you, it would be double as annoying! But if you could make a matching buzzing sound yourself, it would cancel out the real one, like magic, but not magic, just sound science.

When noise-cancelling headphones detect loud sounds, they use tiny microphones to listen to them. Then, the headphones’ speakers make a sound that’s exactly opposite, like saying “Boo!” when someone says “Hello!", and this opposite sound cancels out the real one.

Think about it like playing with your friend in the hallway. If they shout loudly, you can shout back with the same loudness but say something different. The two sounds meet and make a quieter place for you to talk, that’s how noise-cancelling headphones work!