system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do you preceive some kind of "pressure" when using noise canceling headphones?

So I was searching for posts concerning noise canceling headphones and I found a few posts about how they cancel out noise.
As I understand, the headphones basically listen for incoming "noise" and send out the "opposite" wave. OK!

Then I was wondering: if the two waves cancel each other out, why you perceive some kind of "pressure" especially when no music is played?
gpt
This is a fun one. Our brains react to certain input from our senses based on instinct. When you put on noise canceling headphones they cancel out low-frequency outside sounds (and other frequencies). But that lack of low frequencies is also what happens naturally when there is a pressure difference between your inner and outer ear, and it triggered that feeling. It's an instinct reacting to what normally would be a good time to pop your ears, but its the headphones not climbing a mountain or whatever would normally cause a pressure difference.