system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How come sometimes when yawning you get a crackle in your ears?
gpt
Yawning can open your Eustachian tube, which allows pressure to equalize inside your ear. If the pressure isn't equal, it can pull your eardrum taut. The 'crackle' is the eardrum moving, which as you may know, is part of the mechanism that signals your brain about sounds.