Hearing Disorders

Problems with the outer, middle and inner ear can affect hearing, speech and balance. In particular, hearing disorders can affect the auditory and/or vestibular (balance) mechanism at any level. Hearing disorders in children can sometimes lead to speech disorders, as reduced auditory input can result in difficulty learning language.

Common Disorders of Hearing and Hearing Loss

Hearing loss can be classified as one of several types, including:

• Conductive hearing loss, which results from a problem in the middle ear
• Sensorineural hearing loss, which results from a problem in the inner ear
• Mixed loss, which has components of both types of hearing loss.

When structures of the outer, middle or inner ear aren't working properly, sound can't be conducted from outside the ear to the brain to be processed and understood. Hearing loss can have a variety of causes, including age, noise exposure and several different hearing disorders:

• Auditory neuropathy refers to damage to the auditory nerve, which prevents information from the ear structures from being transmitted to the brain.
• Otosclerosis involves abnormal bony growths around the bones in the middle ear (ossicles). These bones transmit sound information through movement, and when they cannot move, the result is reduced hearing acuity.
• Tinnitus is a sensation of ringing or buzzing in the ears, when no actual sound is present.

Balance Disorders

Structures of the vestibular system, which help to control balance and awareness of the body's place in space, are housed in the inner ear. Therefore, disorders and conditions that affect the inner ear can also lead to problems with balance:

• Meniere's disease affects the ear's vestibular system, often causing sudden, debilitating attacks of dizziness. Meniere's disease can also cause hearing loss.
• Vertigo is a disturbance of the vestibular structures in the middle ear, which leads to dizziness and loss of balance.
• Ear Infections and Ear Pain

Infections can occur in the outer, middle and inner ear. These infections can cause ear pain and discomfort, and if they become serious, they can lead to permanent damage in the ear:

• Cholesteatoma is an abnormal growth of cells on the eardrum. Infection can develop as a result, causing damage to affected parts of the hearing mechanism.
• Otitis externa is an infection of the outer ear canal caused by bacteria. It often develops after water washes away the ear canal's protective layer of wax (hence its common name, "swimmer's ear").
• Otitis media is an infection of the middle ear. This is common in children and can occur when pressure in the middle ear is not equalized, sometimes leading to infection.

Auditory Processing Disorders

The hearing process can also be affected beyond the structures of the ear and auditory nerve. Central auditory processing disorder (CAPD) is a communication disorder characterized by problems with processing the auditory information sent to the brain via the auditory nerve, and assigning meaning to sounds, including speech. Though their auditory structures function normally, individuals with CAPD still have trouble understanding auditory information.

Resources

American Speech-Language-Hearing Association Staff. (n.d.). Causes of hearing loss in adults. Retrieved March 22, 2010, from American Speech-Language-Hearing Association Web site: http://www.asha.org/public/hearing/disorders/causes_adults.htm.

Massachusetts Eye and Ear Infirmary Staff. (n.d.). Otosclerosis. Retrieved March 22, 2010, from Massachusetts Eye and Ear Infirmary Web site: http://www.masseyeandear.org/for-patients/patient-guide/patient-education/diseases-and-conditions/otosclerosis/.

Mayo Clinic Staff. (n.d.). Benign paroxysmal positional vertigo. Retrieved March 22, 2010, from Mayo Clinic Web site: http://www.mayoclinic.com/health/vertigo/DS00534.

National Institute on Deafness and Other Communication Disorders Staff. (n.d.). Auditory processing disorders in children. Retrieved March 22, 2010, from National Institute on Deafness and Other Communication Disorders Web site: http://www.nidcd.nih.gov/health/voice/auditory.asp.