Hearing problems affect approximately 17 percent of the adult population in the United States, reports the National Institute on Deafness and Other Communication Disorders. Congenital and acquired hearing problems also occur in children. Hearing loss occurs because of problems with the conduction of sound--conductive hearing loss--or the reception and processing of sound--sensorineural hearing loss. Various disorders affecting the ear structures can also lead to conductive or sensorineural hearing loss.
External Ear Conductive Disorders
The external ear consists of the outer ear and the ear canal, which leads to the eardrum. These structures capture sound waves and direct them toward the eardrum. Disorders that block or deform these structures can lead to conductive hearing loss. Otitis externa, or swimmer's ear, represents an infection of the ear canal. Tissue swelling can block the ear canal, causing decreased hearing, notes the American Academy of Otolaryngology--Head and Neck Surgery. A buildup of earwax, or a cerumen impaction, can also cause conductive hearing loss due to ear canal blockage. External ear-related hearing loss typically resolves with treatment of the underlying disorder.
Middle Ear Conductive Disorders
The middle ear includes the eardrum and three minute bones, the ossicles, which capture and amplify sound waves that are then transmitted to the inner ear. Middle ear problems can cause acute or chronic conductive hearing loss. Otitis media, inflammation or infection of the middle ear, is a common cause of middle ear-associated hearing loss. Acute middle ear infections typically cause temporary conductive hearing loss. Accumulation of fluid and pus limits movement of the eardrum and ossicles. Fluid may persist in the middle ear after an infection, or accumulate due to allergies or exposure to environmental irritants such as cigarette smoke. This condition, known as otitis media with effusion, can cause conductive hearing loss. The National Institute on Deafness and Other Communication Disorders explains that persistence of middle-ear fluid for three months or longer may necessitate placement of ear tubes to relieve pressure and restore hearing. Less common middle-ear disorders that may cause conductive hearing loss include eardrum rupture, tumors, and damage, scarring or malformation of the ossicles.
Inner Ear Sensorineural Disorders
Exposure to loud noise frequently damages the inner ear structures, causing sensorineural hearing loss. The National Institute on Deafness and Other Communication Disorders reports that approximately 26 million adults in the United States have noise-induced hearing loss. Presbycusis, or age-related hearing loss, also occurs because of impaired inner ear function. This form of hearing loss typically affects the capacity to perceive high-pitched sound, which can interfere with the ability to hear the spoken word clearly. Less common inner ear disorders associated with sensorineural hearing loss include Meniere's disease, inner ear infections and ototoxicity--damage due to toxic chemicals or medications.
References
- National Institute on Deafness and Other Communication Disorders: Quick Statistics
- American Speech-Language-Hearing Association: Type, Degree, and Configuration of Hearing Loss
- American Academy of Otolaryngology--Head and Neck Surgery: Swimmer's Ear
- American Academy of Otolaryngology--Head and Neck Surgery: Earwax
- National Institute on Deafness and Other Communication Disorders: Otitis Media
