Hearing Tests

Why It Is 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. The U.S. Preventive Services Task Force suggests that all newborns be screened for hearing loss^{footnote 1}. All 50 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.^{footnote 2}
• 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.

How To Prepare

• Avoid loud noises for 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.

How It Is Done

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.

How long the test takes

• The tests usually take about 1 hour.

How It Feels

This test usually doesn't cause any pain or discomfort.

Risks

There are no known risks from having this test.

Results

Hearing test results

Normal

You are able to hear whispered speech correctly. You can hear tones at equal loudness in both ears. You are able to repeat 90% to 95% of the words in a word recognition test. The microphone finds emissions from the inner ear in otoacoustic emissions testing. The values recorded on the graph for auditory brain stem response testing show that the nerves in the brain that help with hearing are working as they should.

Abnormal

You are not able to hear the whispers during a whispered speech test. Or you are able to hear with one ear but not with the other ear. You hear the tone more loudly in one ear than in the other ear. You can only hear certain sounds at high decibel levels. You can hear sounds, but you can't understand words. No emissions are found from the inner ear in otoacoustic emissions testing. The values recorded on the graph for auditory brain stem response testing show that the nerves in the brain that help with hearing are not working as they should.

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 0 dB to 25 dB. For children, the normal range is 0 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:

Hearing loss table

Hearing threshold in decibels (dB)	Degree of hearing loss	Ability to hear speech
0–25 dB	None	No significant trouble hearing.
26–40 dB	Mild	Trouble with faint or distant speech.
41–55 dB	Moderate	Trouble with conversational speech.
56–70 dB	Moderate to severe	Speech must be loud; trouble with group conversation.
71–90 dB	Severe	Trouble with loud speech. Understands only shouted or amplified speech.
91+ dB	Profound	May not understand amplified speech.