system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Loud music in both ears is comfortable and fine, remove an earphone, and now the music is damagingly loud, why?

Whenever I listen to music and I put it loud, it's comfortable for me. However, the second I take out one earphone, my other ear start to hurt due to the music suddenly being too loud.

Why does it hurt for one case and not the other?
gpt
When both ears have loud music in then, the volume in both ears is the same, and your brain doesn't have a refference to know what a normal volume is. When you take one earbut out, suddenly your brain realizes how much quieter the outside world is, and realizes that you have been listening to your music too loud.