This is nice!
TropicalDingdong@lemmy.world 3 days ago
So lets talk about constructive versus destructive interference.
First off, waves are waves. When you have something like a fan, its generating a series of waves. These waves are typically coming at a constant frequency. The frequency here matters.
Sound travels in waves. These waves are pressure waves in a fluid. Those waves don’t just get absorbed by hard surfaces; they reflect or refract. But those waves are both moving through the space, and themselves have a frequency.
This is important because of this you get patterns of constructive and destructive interference in space.
In some areas of a space there will be amplification, because the frequencies are lining up. In some spaces, the waves will cancel out. Those areas will be quieter.
This phenomena is true for all waves.
medem@lemmy.wtf 3 days ago
whaleross@lemmy.world 3 days ago
OP: Destructive interference as illustrated here is the basis of active noise cancellation (ANC) in headphones.
In theory it is a microphone on the outside of the headphones that has the outside sound inverted and mixed into whatever is playing from the speakers inside the headphones. The undesired outside noise reaches inside the headphones at the same time as the inverted signal is played so that they cancel each other out.
In reality there is some more complexity, as always, but it’s the core principle.