Test Overview

A hearing (audiometric) test is part of an examination 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.

Some 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. All babies born in Alberta are eligible for hearing screening.
• To screen or test children and teens for hearing loss. Hearing loss in children and teens can start or get worse at any time. In children, normal hearing is important for proper language development. Some speech, behaviour, and learning problems in children can be related to problems with hearing.
• 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 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

• Learn how to prepare and what to expect at hearing test appointments for adults
• Learn how to prepare and what to expect for children's hearing test appointments

How It Is Done

Otoscopy

Before starting a hearing test, the audiologist will look in the ear with a special flashlight called an otoscope. The audiologist is looking to see if there is wax in the ear canal and they are checking the condition of the eardrum.

If they find excessive wax, they may recommend removing the wax before the hearing test. If they see a hole in the eardrum or fluid behind the eardrum, the audiologist may recommend a follow-up visit with your doctor.

Pure tone audiometry

A machine called an audiometer plays a series of tones through headphones. The tones change in pitch and loudness. Your audiologist 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 audiologist 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. Sounds are then sent through earphones. The electrodes monitor your brain's response to the sounds and record the response on a graph.

How long the test takes

• The tests usually take about 1 hour.
• ABR testing may take 1 to 3 hours depending on the reason for the test and the age of the person being tested.

How It Feels

During the hearing test you will sit in a quiet sound treated room. This test usually doesn't cause any pain or discomfort.

Results

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. Most speech sounds occur in the range of 250 to 8,000 Hz.
• Intensity, or loudness, is measured in decibels (dB). The normal range (threshold or lower limit) of hearing is 0 dB to 20 dB.

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. Your audiologist will review the test results with you, answer your questions, and give recommendations based on the test results.