Alternative Names audiology test, audiometry, audiogram, audiography
Definition A hearing test determines how well a person can hear different sounds.
How is the test performed? Sounds are transmitted by sound waves that travel through the air and through bone. A hearing test usually determines how well a person hears sounds that are presented to the ear and to the skull bones.
Testing for sounds that travel through the air is done with a person wearing earphones over his or her ears. Pure tones of various frequencies are presented to one ear at a time at controlled volumes. The person being tested is asked to indicate when he or she first hears the sound. The softest sounds that the person can detect are recorded for each frequency. The results are put on a graph and compared to a normal hearing graph, or audiogram.
To test for sounds that travel through the bone, tuning forks of different frequencies are tapped and held against a person's skull. The person being tested is asked to indicate which sounds he or she can detect.
What is involved in preparation for the test? A doctor will provide specific instructions.
What do the test results mean? The loudness of sound is measured in units called decibels (dB). A soft sound, such as normal speech, ranges from 5 to 10 dB. A loud sound, such as a jet plane taking off nearby, is about 180 dB. Loud music, such as rock concerts, can reach 80 to 120 dB. Sounds louder than 85 dB can cause hearing loss.
A person with normal hearing can detect low tones (frequencies of 64 cps, or cycles per second) at 1 to 2 dB and high tones (around 11,500 cps) at 10 dB. Most tones in between these extremes can be heard at less than 10 dB.
If a person cannot detect pure tones below 10 dB, some hearing loss may be present.
Conditions that may lead to hearing loss are:
acoustic neuroma, which is a non-cancerous growth of the acoustic nerve in the ear canal
acoustic trauma, which is hearing loss caused by loud noise that occurs slowly over time
Author: David T. Moran, MD Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
