The speaker sends out a tone at a very high frequency. That frequency is particular that it actually interrupts noise outside.
Think of if you run your ear aggressively as if you're itchy, you might get a high eering tone afterwards. You may also have noticed you don't hear anything for a few seconds. That's the whole concept of noise cancellation.
Sparquee t1_j2coklw wrote
Reply to Eli5 How exactly does Noise cancellation work? That too in such small airbuds by Professional-Ad3441
The speaker sends out a tone at a very high frequency. That frequency is particular that it actually interrupts noise outside. Think of if you run your ear aggressively as if you're itchy, you might get a high eering tone afterwards. You may also have noticed you don't hear anything for a few seconds. That's the whole concept of noise cancellation.
Hope this helps.