Hearing tests

Hearing tests check how well you can hear. There are many types of hearing tests. If your doctor thinks that you might have hearing loss, you may be referred to a hearing specialist (audiologist) to have hearing tests done.

Hearing tests may be done:

• To check, or screen, babies and young children for hearing problems that might affect their ability to learn, speak, or understand language. Experts recommend that all newborns be screened for hearing loss . Many states require newborn hearing tests for all babies born in hospitals. Also, many health groups and doctors' groups suggest routine screening. Talk to your doctor about whether your child has been or should be tested.
• To screen children and teens for hearing loss. Hearing should be checked by a doctor at each well-child visit. In children, normal hearing is important for proper language development. Some speech, behavior, and learning problems in children can be related to problems with hearing. For this reason, many schools provide hearing tests when children first begin school. The American Academy of Pediatrics suggests a formal hearing test at ages 4, 5, 6, 8, and 10 years.
• To test for possible hearing loss in anyone who has noticed an ongoing hearing problem in one or both ears or has had a hard time understanding words in conversation.
• To screen for hearing problems in older adults. Hearing loss in older adults is often mistaken for a reduced mental ability. (For example, a person may seem to not listen or respond to conversation.)
• To screen for hearing loss in people who are often exposed to loud noises or who take certain antibiotics, such as gentamicin.
• To find out the type and amount of hearing loss (conductive, sensorineural, or both). In conductive hearing loss, the movement of sound (conduction) is blocked or does not pass into the inner ear. In sensorineural hearing loss, sound reaches the inner ear, but a problem in the nerves of the ear or, in rare cases, the brain itself prevents proper hearing.

Before the test

Before you start any hearing tests, your ear canals may be checked for earwax. Wax can affect how well you hear. Any hardened wax may be removed.

If you wear hearing aids, you may be asked to remove them for some of the tests.

Tuning fork tests

Your doctor strikes the tuning fork to make it vibrate and produce a tone. Sometimes the tuning fork will be placed on your head or behind your ear.

Pure tone audiometry

A machine called an audiometer plays a series of tones through headphones. The tones change in pitch and loudness. Your doctor will reduce the loudness of a tone until you can no longer hear it. Then the tone will get louder until you can hear it again. If you can hear the tone, you signal by raising your hand or pressing a button.

The headphones will then be removed. A special vibrating device will be placed on the bone behind your ear. Again, you will signal each time you hear a tone.

Speech reception and word recognition tests

In these tests, you hear a series of simple words spoken with different degrees of loudness. You are asked to repeat the words. Your doctor measures the level at which you can no longer hear the words well enough to repeat them.

Auditory brain stem response (ABR) testing

In this test, electrodes are placed on your scalp and on each earlobe. Clicking noises are then sent through earphones. The electrodes monitor your brain's response to the clicking noises and record the response on a graph.

• Try to avoid loud noises for 12 to 16 hours before you have a thorough hearing test.
• Tell your doctor if you take or have taken antibiotics that can damage hearing, such as gentamicin.

Sound is described in terms of frequency and intensity. Your hearing threshold is how loud the sound of a certain frequency must be for you to hear it.

• Whether a sound is low or high is measured in vibrations per second, or hertz (Hz). This is called frequency, or pitch. The human ear can normally hear frequencies from a very low rumble of 16 Hz to a high-pitched whine of 20,000 Hz. The frequencies of normal speech in a quiet place are 500 Hz to 2,000 Hz.
• Intensity, or loudness, is measured in decibels (dB). The normal range (threshold or lower limit) of hearing is -10 dB to 15 dB. Normal results show that you hear within these ranges in both ears.

The following table relates how loud a sound must be for a person to hear it (hearing thresholds) to the degree of hearing loss for adults: