The external, middle and inner ear, the hearing or auditory nerves, and the brain all contribute to the process of hearing. Abnormalities in any of these structures can lead to impaired hearing. Some types of hearing loss are reversible, especially those affecting the external and middle ear. Hearing loss related to the inner ear and auditory nerves is usually permanent. Determining the cause of hearing loss is the first step in instituting appropriate treatment for impaired hearing.
Otitis Externa
Otitis externa, or swimmer's ear, is a painful infection of the ear canal. The American Academy of Otolaryngology (AAO) notes that increased moisture in the ear canal is often a contributing factor to the development of otitis externa. Swelling of the ear canal due to the infection may interfere with the transmission of sound waves to the middle ear, causing a temporary hearing loss in the affected ear. Resolution of the infection leads to restoration of normal hearing.
Otitis Media with Effusion
Inflammation of the middle ear with fluid accumulation behind the eardrum is termed otitis media with effusion. This condition is common in children; it may occur in adults. The eardrum is a thin piece of skin at the end of the ear canal, which normally moves in response to sound. The movement conducts impulses through the bones of the middle ear to the inner ear. The presence of fluid in the middle ear limits the normal movement of the eardrum causing impaired hearing. According to the American Academy of Family Physicians' "Clinical Practice Guideline: Otitis Media with Effusion," children with symptoms persisting for four months or longer may be candidates for ear tubes. Ear tubes are small devices placed in the eardrum that permit drainage of middle ear fluid with restoration of eardrum movement and recovery of normal hearing.
Noise-Induced Hearing Loss
The inner ear contains tiny hair cells. The movements of these hair cells in response to sound waves conducted from the middle ear lead to transmission of impulses through the auditory nerves to the brain. The brain processes the information leading to sound recognition and understanding. The National Institute on Deafness and Other Communication Disorders warns that loud noise can damage the hair cells causing permanent hearing loss. Isolated exposure to extremely loud noise, such as an explosion, can cause permanent damage. More commonly, chronic exposure to loud noise is the culprit of noise-induced hearing loss. According to the American Speech-Language-Hearing Association, examples of potentially ear-damaging sound include noise from truck traffic, shop tools, lawn mowers, firearm discharges, jet engines and amplified music.
Presbycusis
Progressive, gradual hearing loss associated with advancing age is termed presbycusis. The Mayo Clinic reports an estimated one-third of Americans between ages 65 to 75 have some level of presbycusis. Loss of sensitivity to high-pitched sounds is typically greatest, according to the National Institute on Deafness and Other Communication Disorders. Presbycusis is a permanent form of hearing impairment. Hearing aids and other assistive devices can help minimize the effects of presbycusis on normal communication.
