Think of your middle ear as a tiny, air-filled cave. Its only door to the outside world is the Eustachian tube—a narrow, floppy passageway that runs to the back of your throat. Normally, this tube opens with every swallow or yawn to equalize pressure. Barotrauma happens when the pressure outside changes faster than your stubborn Eustachian tube can handle, creating a painful vacuum that pulls at your eardrum, sucks in fluid, or, in severe cases, causes the drum itself to rupture.