Eli5: can you scale up noise cancellation technology, like in headphones, and if yes, by how much?

Question

Could you noise cancel a room, or even an area in the outdoors?

In: Engineering

Answer 1

Not for multiple listeners unless the source of the noise is a single point and your cancelling speakers can emulate that single point – as an example, the noise cancelling sound wave for listener 1 will not reach listener 2 at the correct time to cancel the noise, but could instead amplify it if it’s in phase.

For a single listener, though, any size space can work as long as the cancelling speakers are closer to you than the source of the noise. The math is difficult but computers are good with math.