Most people think of hearing tests as merely raising their hand when they hear a soft beeping sound. This is only a small part of a routine hearing evaluation. After the audiologist examines each ear canal and eardrum for overall health and excessive wax, the person is seated in a sound-treated room which allows for the detection of extremely soft sounds. Initially, soft tones are presented and the patient is asked to signal that the tone is heard by either pressing a button or raising his or her hand. Next, speech awareness, detection and discrimination data is obtained. Speech- in – noise tests are utilized to assess understanding ability of speech in the presence of background noise. Using these tests, the audiologist determines whether a hearing loss exists and, if so, its degree and type. The results of these tests are discussed and appropriate treatment options are recommended.
The degree of hearing loss is determined based on the loudness required for a person to hear the soft beeping tones, measured in decibels.
Degrees of Hearing Loss (chart)
0 – 20 decibels
21- 40 decibels
41- 60 decibels
61- 80 decibels
80 + decibels
Hearing losses may be categorized as conductive, sensorineural, a combination of the two called mixed.
Conductive hearing loss is caused by a problem of the outer ear (ear canal) or middle ear (ear drum, tiny ear bones, or the space containing those bones). Conductive hearing loss is quite often medically treatable. When a conductive loss is identified, the patient is referred to a physician, preferably one specializing in the treatment of ear, nose and throat diseases, for evaluation and possible treatment. Some of the most common causes of conductive hearing loss are ear infections (otitis media), trauma to the ear, otosclerosis (a problem with the tiny bones of the ear) and foreign objects in the ear canals.
Sensorineural hearing loss (“nerve” or “inner-ear” hearing loss) is usually caused by a problem with the actual organ of hearing that turns sound into nerve energy. In most cases of sensorineural hearing loss, the tiny hair cells that respond to sound in the inner ear are damaged and cannot send that sound to the nerve and up to the brain. Sensorineural loss is usually permanent and not medically treatable. Fortunately, most sensorineural losses can be treated successfully with amplification. The two most common causes of sensorineural hearing loss are noise exposure and the normal aging process.
Retrocochlear hearing loss. Occasionally, sensorineural hearing loss is related to an actual problem with the hearing nerve or parts of the brain which process speech. These types of losses are called retrocochlear disorders. When a retrocochlear disorder is suspected, additional tests such as auditory brainstem response (ABR) or electronystagmography (ENG) may be recommended to provide additional information. Otoacoustic emissions (OAEs) also may be of benefit in evaluating such hearing losses. Patients with suspected retrocochlear disorders are referred to a physician for further evaluation.