system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why do we find the sound of the rain soothing but can't sleep if there's a tap dripping?
gpt
rainfall is randomized, and produces what’s called a broadband sound: a sound which has lots of different frequencies, or pitches, in it.

a dripping faucet is generally pretty regular, like a ticking clock, and each drop creates a sound that is more narrowband: it has fewer frequencies, sometimes even to the point of being a discernible musical note. it also has a single discernible moment when the sound happens.

put all that together and what you get is that the dripping faucet grabs your attention several different ways, and when your attention is focused on something, you can’t sleep because your brain is like “i’m working on something here! can’t sleep until we’re done with it!”

the rain has no features to latch onto, and in fact its broadband nature means it masks other intermittent sounds which might otherwise catch your attention. by giving you nothing to pay attention to, the rain allows your brain to relax and drift off.