American Medical Association Family Medical Guide - American Medical Association [715]
In a healthy ear, the air pressure inside and outside the eardrum is the same. This equilibrium allows the eardrum to vibrate freely when sound waves hit it. The vibrations pass through the ear to enable us to hear, and reflect back into the air. Too much or too little air pressure on the inner side of the eardrum makes the eardrum too stiff to conduct sounds properly—more sound is reflected back, and less passes through to the inner ear.
The impedance test, or tympanometry, measures the ability of the eardrum to pass sound waves to the inner ear and detects abnormal air pressure in the middle ear, fluid in the middle ear, perforation of the eardrum, and disorders of the tiny sound-conducting bones of the middle ear. In this test, a probe covered with an airtight material (usually plastic) is inserted into the outer ear canal to seal the entrance to the ear. A transmitter in the probe pumps air through the probe to change the air pressure in the ear canal and then directs sounds to the eardrum. A receiver in the probe measures how well the eardrum absorbs the sounds. The probe has a tiny speaker (sound transmitter) and a tiny microphone (sound receiver). The difference between the sound transmitted and the sound received is the sound absorbed. Several measurements are made at different pressure levels.
Brain stem auditory evoked response test
The brain stem auditory evoked response test is a computerized hearing test that measures electrical responses in the brain stem (the part of the brain that controls basic functions) in reaction to sounds. In this test, electrodes are attached to the scalp and earlobes. You listen to clicking sounds through headphones, and a computer records the electrical activity of the brain in response to the sounds. The brain stem auditory evoked response test is used to evaluate the hearing of otherwise untestable people, such as infants, and is helpful in ruling out benign (noncancerous) tumors that can develop in the nerves involved in balance and hearing (called acoustic neuromas).
Treatment
Treatment of hearing loss depends on the cause. Conductive hearing loss can usually be corrected and hearing restored by treating the underlying cause. For example, if earwax causes hearing loss, a doctor will remove the wax. Sensorineural hearing loss often cannot be corrected. However, in some people, devices such as a cochlear implant (see next page) can help restore some hearing. A number of other devices—such as hearing aids (see below), assistive devices (see next page), and alerting devices (see page 1020)—are available that can improve a person’s hearing and his or her quality of life.
MY STORY Hearing Loss
I noticed over the past few years that my father’s hearing wasn’t what it used to be. He would increase the volume on the TV and radio, and my mom would ask him to lower it because it was too loud. During conversations he often asked people to repeat themselves. I suggested that he have a hearing test, but he said his hearing was fine. He was once very active, but my mom said he started becoming more and more withdrawn and lost interest in social gatherings. He eventually stopped communicating with his friends and family because he was embarrassed about his hearing problem.
One day my mom called me and said my father had agreed to have a hearing test. After an ear examination and several tests, he was told he needed a hearing aid. The doctor told him that some hearing loss is common as a person gets older and referred him to an audiologist. The audiologist talked to my father about all the different kinds of hearing devices that are available and helped him choose the right kind of hearing aid. Now my father can hear again and has resumed his social life. He says his only regret was not having a hearing test sooner.
Now my father can hear again and has resumed his social life. He says his only regret was not having a hearing test sooner.