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    Hearing Tests

    Test Overview

    A hearing (audiometric) test is part of an ear exam that tests how well a person is able to hear. It is done by measuring how well sound can reach the brain.

    The sounds we hear start as vibrations in the air around us. The vibrations make sound waves, which vibrate at a certain speed (frequency) and have a certain height (amplitude). The vibration speed of a sound wave determines how high or low a sound is (pitch). The height of the sound wave determines how loud the sound is (volume).

    Hearing happens when these sound waves travel through the ear and are turned into nerve impulses. These nerve impulses are sent to the brain, which "hears" them.

    • Sound waves enter the ear through the ear canal (external ear). Then they strike the eardrum (tympanic membrane). The eardrum separates the ear canal and the middle ear.
    • The eardrum vibrates, and the vibrations move to the bones of the middle ear. In response, the bones of the middle ear vibrate, which boosts the sound and sends it to the inner ear.
    • The fluid-filled, curved space of the inner ear, sometimes called the labyrinth, contains the main sensory organ of hearing. This organ is called the cochlea. Sound vibrations cause the fluid in the inner ear to move, which bends tiny hair cells (cilia) in the cochlea. The movement of the hair cells creates nerve impulses. These nerve impulses then travel along the cochlear nerve to the brain and are read as sound.

    Hearing tests help find what kind of hearing loss you have. The tests measure how well you can hear sounds that reach the inner ear through the ear canal. They also measure sounds that are spread through the skull.

    Most hearing tests ask you to respond to a series of tones or words. But there are some hearing tests that do not require a response.

    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

    Tell your doctor if:

    • You have recently been exposed to any painfully loud noise or to a noise that made your ears ring. Avoid loud noises for 16 hours before you have a thorough hearing test.
    • You take or have taken antibiotics that can damage hearing, such as gentamicin.
    • You have had any problems hearing normal conversations or have noticed any other signs of possible hearing loss.
    • You have recently had a cold or an ear infection.

    Before you start any hearing tests, your ear canals may be checked for earwax. This can affect how well you can hear the tones or words during testing. Hardened wax may be removed.

    You may wear headphones for some tests. You will need to remove eyeglasses, earrings, or hair clips that can affect the placement of the headphones. The person giving the test will press on each ear to find out if the pressure from the headphones on your outer ear will cause the ear canal to close. If so, a thin plastic tube may be placed in the ear canal before the testing to keep your ear canal open. The headphones are then placed on your head and adjusted to fit.

    If you wear hearing aids, you may be asked to remove them for some of the tests. You may be asked to shampoo your hair before you have auditory brain stem response (ABR) testing.

    Talk to your doctor about any concerns you have about the need for a hearing test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form (What is a PDF document?) .

    How It Is Done

    Hearing tests can be done in an audiometry (hearing) lab by a hearing specialist (audiologist). They can also be done in a doctor's office, a school, or the workplace by a nurse, a health professional, a psychologist, a speech therapist, or an audiometric technician.

    Whispered speech test

    In a whispered speech test, the health professional will ask you to cover the opening of one ear with your finger. He or she will stand 1 ft (0.3 m) to 2 ft (0.6 m) behind you and whisper a series of words. You will repeat the words that you hear. If you can't hear the words at a soft whisper, the health professional will say the words more loudly until you can hear them. Each ear is tested separately.

    Pure tone audiometry

    Pure tone audiometry uses a machine called an audiometer to play a series of tones through headphones. The tones vary in pitch (frequency, measured in hertz) and loudness (intensity, measured in decibels). The person doing the test will control the volume of a tone. He or she will reduce its loudness until you can no longer hear it. Then the tone will get louder until you can hear it again. You signal by raising your hand or pressing a button every time you hear a tone, even if the tone you hear is very faint. The person will then repeat the test several times, using a higher-pitched tone each time. Each ear is tested separately. 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.

    Tuning fork tests

    A tuning fork is a metal, two-pronged device that makes a tone when it vibrates. The person giving the test hits the tuning fork to make it vibrate and produce a tone. These tests check how well sound moves through your ear. Sometimes the tuning fork will be placed on your head or behind your ear. Depending on how you hear the sound, the person giving the test can tell if there is a problem with the nerves or with sound getting to the nerves.

    Speech reception and word recognition tests

    Speech reception and word recognition tests measure how well you can hear and understand normal speech. In these tests, you are asked to repeat a series of simple words spoken at different volumes. A test called the spondee threshold test finds the level at which you can repeat at least half of a list of familiar two-syllable words.

    Otoacoustic emissions (OAE) testing

    Otoacoustic emissions (OAE) testing is often used to check newborns for hearing problems. In this test, a small, soft microphone is placed in the baby's ear canal. Sound is then sent through a small flexible probe that has been put in the baby's ear. The microphone detects the inner ear's response to the sound. This test can't tell the difference between conductive and sensorineural hearing loss.

    Auditory brain stem response (ABR) testing

    Auditory brain stem response (ABR) testing checks for sensorineural hearing loss. In this test, electrodes are placed on your scalp and on each earlobe. Clicking noises are then sent through earphones. The electrodes track your brain's response to the clicking noises and record the response on a graph. This test is also called brain stem auditory evoked response (BAER) testing or auditory brain stem evoked potential (ABEP) testing.

    How It Feels

    It is not painful to have a hearing test.

    Risks

    Having a hearing test does not cause problems.

    Results

    A hearing test is part of an ear exam that tests how well a person can hear.

    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.

    What Affects the Test

    You may not be able to have the test, or the results may not be helpful, if:

    • You are not able to follow directions or understand speech well enough to respond during most tests. It may be hard to do hearing tests on young children or on people who have physical or mental disabilities.
    • There is background noise or equipment problems, such as cracked or poorly fitting headphones or an uncalibrated audiometer.
    • You have a hard time speaking or understanding the language of the tester.
    • You have had a recent cold or ear infection.
    • You have been around loud noises within 16 hours before the test.

    What To Think About

    • Other types of tests may be used to check hearing. These tests include:
      • Acoustic immittance testing. This 2- to 3-minute test measures how well the eardrum moves in response to sound. The soft tip of a small tool is put into the ear canal and adjusted to make a tight seal. Sound and air pressure are then sent toward the eardrum. The test is not painful. But you may feel slight changes in pressure or may hear the tone.
      • Vestibular tests. These tests look for problems with areas of the inner ear that help control balance and coordination. During these tests, you try to maintain balance and coordination while being asked to move in many different ways, with your eyes open and closed. The person giving the test will make sure that you do not fall. You don't need to do anything to prepare for these tests.

    References

    Citations

    1. U.S. Preventive Services Task Force (2008). Universal Screening for Hearing Loss in Newborns: Recommendation Statement. Available online: http://www.uspreventiveservicestaskforce.org/uspstf08/newbornhear/newbhearrs.htm.
    2. Committee on Practice and Ambulatory Medicine, Bright Futures Periodicity Schedule Workgroup (2014). 2014 recommendations for pediatric preventive health care. Pediatrics, published online February 24, 2014. DOI: 10.1542/peds.2013-4096. Accessed March 7, 2014.

    Other Works Consulted

    • Committee on Practice and Ambulatory Medicine, Bright Futures Periodicity Schedule Workgroup (2014). 2014 recommendations for pediatric preventive health care. Pediatrics, published online February 24, 2014. DOI: 10.1542/peds.2013-4096. Accessed March 7, 2014.

    Credits

    ByHealthwise Staff
    Primary Medical Reviewer William H. Blahd, Jr., MD, FACEP - Emergency Medicine
    Specialist Medical Reviewer Charles M. Myer, III, MD - Otolaryngology

    Current as ofFebruary 17, 2015

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