Chapter 7 The Sensory Systems 281 Otitis externa can be prevented by thoroughly cleaning and drying the ear canal with a mild alcohol-based solution after swimming, or by avoiding immersion of the ears. Otitis Media Otitis media is an infection of the middle ear caused by bacteria or a virus. It is usually associated with an upper respiratory tract infection. Otitis media is relatively common in infants and toddlers because their Eustachian tubes are not yet fully developed. Symptoms of otitis media include pain, swelling, and the production of fluid or pus. Viral infections do not respond to antibiotics but often improve with time. Mild to moderate middle ear infections caused by bacteria are treated with antibiotics. More serious bacterial infections that do not respond well to antibiotics are frequently treated by a surgical procedure. During the surgery, tiny tubes are inserted into the tympanic membrane. These tubes alleviate the elevated pressure in the inner ear. Labyrinthitis Labyrinthitis (lab-uh-rin-THIGH-tis) is an infection of the inner ear that produces inflammation (swelling). It can be caused by inflammation of a Tinnitus Tinnitus (TIN-i-tus) is a condition that causes a sound like ringing to be heard in the ear. Tinnitus occurs when the hair cells in the organ of Corti that stimulate the auditory nerve are damaged. Normal movement of the hair cells is triggered by sound waves. When the hair cells have been damaged, however, they sometimes move randomly, generating the ringing sound. What damages these hair cells? The most common culprit is repeated exposure to loud noise, such as loud music. Other causes include overuse or long-term use of certain medications, including nonsteroidal anti-inflammatory drugs (NSAIDs). Tinnitus is a common and growing problem. According to the American Tinnitus Association, some 50 million people in the United States suffer from the disorder. Otitis Externa Have you ever gone swimming in a lake and then later developed an earache? You might have had swimmer’s ear, formally known as otitis (oh-TIGH-tis) externa. This bacterial or fungal infection of the auditory canal is caused by immersion in contaminated water. Symptoms may include itching, pain, fever, and, in extreme cases, temporary hearing loss. What Research Tells Us …about Tone-Deafness You may have noticed that some people have difficulty singing in key with music. It is typically said of such people that they cannot “carry a tune.” A person who sings off-key has amusia (uh-MYOO-zee-uh). Amusia is characterized by the inability to distinguish differences in pitch (that is, how high or low a tone is) as well as the inability to remember melodies. Amusia is present in about 3% of people from birth, but it can also result from a brain injury. Researchers studying this condition have tried to train amusic children to develop the ability to better hear and reproduce musical tones. One method used by the researchers consists of having the children repeatedly listen to popular music for one month. This training, however, has had no apparent effect. Studies of brain activity in amusic individuals indicate that this difficulty in processing musical tones is caused by poor neural connections between the auditory center in the brain and the other related areas of the brain. Taking It Further 1. Can you carry a tune? Sing a favorite song to friends or relatives, then listen to them as they sing. Compare the results. 2. Do some research on the causes of and treatments for amusia. Share your findings with the class. Copyright Goodheart-Willcox Co., Inc.