Audiometry

Definition

An audiometry exam tests your ability to hear sounds. Sounds vary, based on their loudness (intensity) and the speed of sound wave vibrations (tone).

Hearing occurs when sound waves stimulate the nerves of the inner ear. The sound then travels along nerve pathways to the brain.

Sound waves can travel to the inner ear through the ear canal, eardrum, and bones of the middle ear (air conduction). They can also pass through the bones around and behind the ear (bone conduction).

The INTENSITY of sound is measured in decibels (dB):

Sounds greater than 85 dB can cause hearing loss after a few hours. Louder sounds can cause immediate pain, and hearing loss can develop in a very short time.

The TONE of sound is measured in cycles per second (cps) or Hertz:

The normal range of human hearing is about 20 to 20,000 Hz. Some animals can hear up to 50,000 Hz. Human speech is usually 500 to 3,000 Hz.

How the Test is Performed

Your health care provider may test your hearing with simple tests that can be done in the office. These may include completing a questionnaire and listening to whispered voices, tuning forks, or tones from an ear examination scope.

A specialized tuning fork test can help determine the type of hearing loss. The tuning fork is tapped and held in the air on each side of the head to test the ability to hear by air conduction. It is tapped and placed against the bone behind each ear (mastoid bone) to test bone conduction.

A formal hearing testing can give a more exact measure of hearing. Several tests may be done:

How to Prepare for the Test

No special steps are needed.

How the Test will Feel

There is no discomfort. The length of time varies. An initial screening may take about 5 to 10 minutes. Detailed audiometry may take about 1 hour.

Why the Test is Performed

This test can detect hearing loss at an early stage. It may also be used when you have hearing problems from any cause.

Normal Results

Normal results include:

What Abnormal Results Mean

There are many kinds and degrees of hearing loss. In some types, you only lose the ability to hear high or low tones, or you lose only air or bone conduction. The inability to hear pure tones below 25 dB indicates some hearing loss.

The amount and type of hearing loss may give clues to the cause, and chances of recovering your hearing.

The following conditions may affect test results:

Risks

There is no risk.

Considerations

Other tests may be used to determine how well the inner ear and brain pathways are working. One of these is otoacoustic emission testing (OAE) that detects sounds given off by the inner ear when responding to sound. This test is often done as part of a newborn screening. A head MRI may be done to help diagnose hearing loss due to an acoustic neuroma.


Review Date: 5/17/2018
Reviewed By: Josef Shargorodsky, MD, MPH, Johns Hopkins University School of Medicine, Baltimore, MD. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. Editorial update 10/01/2018.

This information should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. © 1997- 2007 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.