frzx1 t1_j2dlnsp wrote on December 31, 2022 at 1:50 PM

Reply to comment by chipdipmcgillicuddy in Eli5 How exactly does Noise cancellation work? That too in such small airbuds by Professional-Ad3441

No, you can not hear it, and that's because it's not being played into your ear, it's being laid on top of the sound that's coming into the audio device. There is no significant delay in it because there are fast dedicated chips in the sound devices that do a lot of computational work when it comes to sound waves. So, they're not always doing this in real time, sometimes they're predicting the sound before it's even completely addressed by the device. If there was a gunshot, far away, yes, it would mask it to a certain degree. That degree is what makes noise cancelling good or bad. There's a lot of other stuff that's done to facilitate the sound cancelling, one of them being plugging the ear completely so that no sound wave enter into the ear directly; no ear cavity is left unsealed. Watch THIS video and you'll be amazed to see how apparent this entire process is.

chipdipmcgillicuddy t1_j2dn3k0 wrote on December 31, 2022 at 2:03 PM

I thought about it for a few minutes longer and realized this can work because your wearing something right next to your eardrum. Before I was thinking how could sound be cancelled, if I yell at a concert when the band is playing my yell is still there but it’s drowned out, but I guess because the headphones are right next to your ears that must be a big part of why it works.

Techial t1_j2drnu0 wrote on December 31, 2022 at 2:41 PM

Well, sort of. You also have massive "noise-cancellation" systems built on the same principle when big artists perform live concerts. They literally have subwoofers between the stage and the actual sound-producing subwoofers pointing out to the crowd, and these noise cancelling subwoofers play the same bass sounds (albeit a bit delayed to account for travel) but polarity switched. Imagine sound as a wave going up and down, now if you play the exact same wave but flipped, the waves will cancel out eachother.