Otitis media with effusion, a condition in which fluid sits behind the eardrum for weeks, always causes some degree of hearing loss. Much of this loss is temporary, though it can become permanent, as the American Academy of Otolaryngology–Head and Neck Surgery explains.
Children are more likely than adults to experience otitis media with effusion because their Eustachian tubes are shorter and more horizontal than those of adults, making it more difficult to clear fluid or bacteria, according to the American Academy of Otolaryngology–Head and Neck Surgery. Typically about 24 decibels of hearing are lost when there is fluid behind the eardrum, though this figure can go higher. If the fluid is drained and a tympanostomy tube is inserted, the hearing loss can be temporary.