system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why can you sometimes hear very clearly when you yawn? Is this something that doctors can work with to perhaps fix gearing issues?
gpt
It opens the Eustachian (auditory) tube, part of the middle ear. Normally this isn't open to air, but yawning allows it to exchange air with the outside world and equalize to outside pressure. So yawning when changing altitudes will clear your hearing.