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injury to the ear (less commonly to other organs containing air or gas, such as the lungs and intestines), arising from a sharp change in atmospheric pressure. The tympanic membrane can tolerate even a marked increase in pressure if it occurs slowly, in which case pressure on both sides of the tympanic membrane (on the side of the external auditory meatus and on the side of the tympanic cavity) is equalized through the eustachian tube. In cases of sharp changes (drops) in pressure, for example, in rapid ascents and descents of an airplane, the pressure can be equalized by swallowing (which is why hard candy is given out on an airplane). If the pressure cannot be equalized, the tympanic membrane is sucked in and the pressure is transmitted through the chain of auditory ossicles to the inner ear. At first, a barotrauma is felt as pain in the ear, then hearing is impaired; subsequently, there is noise in the ears and sometimes vertigo. If the drop in pressure is extreme, the tympanic membrane may rupture. Barotrauma occurs in fliers (when diving), parachute jumpers, and divers. Prevention consists in screening persons with clear eustachian tubes for the particular occupations and special training in a pressure chamber.
L. V. NEIMAN