Video narration
How can your headphones make a loud bus or plane seem quieter while your music becomes easier to hear? Ear cups seal out some sound. But noise isn’t a wall; it reaches you as moving waves, with the engine rumbling the air around your ears. Tiny microphones listen to that noise. The headphones quickly process it and create a matching signal turned the other way. The opposite sound is called anti-noise. Here’s the flip: they don’t erase the noise around you. Their speakers add anti-noise, timed extremely precisely, so the two waves meet near your ears and partly cancel. It works best on steady, low sounds like an engine. Sudden voices, claps, and changing noises are harder to reduce, so silence is never perfect. So on that bus or plane, active noise cancellation listens to the noise and adds carefully timed sound—not simply blocking it.