Why do your ears pop on airplanes?
The Real Answer
Your ears pop on airplanes because air pressure on the two sides of your eardrum is being equalized. The middle ear is an air-filled space behind the eardrum, and a narrow passage called the Eustachian tube connects it to the back of your nose and throat.
When the plane climbs or descends, cabin pressure changes. If the pressure outside your eardrum changes faster than the middle-ear pressure can adjust, the eardrum is pushed slightly out of its usual position, which can make your ear feel full, muffled, or uncomfortable. Swallowing or yawning opens the Eustachian tube and lets air move in or out of the middle ear. When the pressures equalize quickly, you feel or hear the familiar pop.
Congestion can make this equalization harder. Ordinary airplane-ear pressure usually settles, but severe or persistent pain or hearing changes after a flight should not be treated as just a stubborn ear pop.
You spend the entire descent swallowing on purpose every five seconds, a bodily function you have otherwise trusted unsupervised your entire life. One ear pops, and now you are doing test swallows until the other one catches up.
Why People Ask This
People ask because the sensation feels mechanical and sudden: hearing can go muffled, pressure builds, and then one swallow or yawn can produce a pop and immediate relief. It feels as though something inside the ear physically moved, so the natural question is what actually changed.