Eli5 How exactly does Noise cancellation work? That too in such small airbuds

Question

Eli5 How exactly does Noise cancellation work? That too in such small airbuds

In: 528

Answer 1

Sound is swinging air. Its like a wave. You have tops and bottoms in the wave.
Noise cancelation records the sound and gives back the opposite spike. Top spikes get cancelled with bottom spikes of same strength and other way round.
This is why you can feel some sort of pressure in your ears, when you have noise cancellation in your ears without actual music, when the outside is loud.