The eardrum is a thin membrane that separates the external ear from the middle ear. A hole (or perforation) in this membrane may develop following infection (otitis media), loud noises, explosions or trauma. Changes in pressure can also cause a rupture, particularly if the Eustachian tubes are blocked; for example when flying with a severe cold.
Although a non-infective perforated eardrum will usually heal by itself, surgery may sometimes be required for those that have become infected.