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

I had the same question a few years ago, this video did a great simple explanation that helped me understand what’s going on

Answer 2

I was told in university that noise cancelling headphones used by jet pilots work by subtracting white noise from the sound they are playing, in the belief that generic “outside noise” was something like white noise (probably not a bad approximation when you are next to a jet engine), and subtracting it has the effect of cancelling it out. This was in the days before noise cancelling was a feature of consumer headphones, but I always assumed the principle was the same.

Answer 3

Sound travels in waves.

The waves have peaks (high spots) and valleys (low spots). Anytime two sound waves collide, if a peak hits a peak or a valley hits a valley, they grow and make the sound more intense.

On the flip side, if a peak hits a valley they cancel each other out, the bigger one still pulls through but with reduced intensity. Or, if a peak hits a valley of the same size, they perfectly cancel out with zero sound. That’s where the headphones come in.

Noise cancelling headphones study the background noise to find out where the peaks and valleys are.

Next, the headphones create their own sound wave that has valleys where the ambient sound has peaks and vice versa. This means the created sound meets the background noise and everything is cancelled (or at the very least dramatically reduced).