Patients who suffer from hearing loss, or other hearing- and balance-related conditions, may benefit from audiologic testing. Comprehensive diagnostic exams can determine the causes and severity of, and best treatment for, hearing-related conditions. Audiologic tests are usually performed after other diagnostic tests have indicated the presence of a possible hearing problem or balance-related condition.
An audiogram uses sounds of specific frequencies and intensity levels to determine what a person can hear in each ear. The sounds are heard through headphones, and the patient is asked to identify each sound and the ear in which it was heard. The sounds become fainter and fainter, ultimately determining the lowest level at which a patient can hear. An audiogram may also include speech in the form of two-syllable words to determine how well a patient can comprehend what is being heard. For results to be considered normal, a patient must be able to hear a normal speaking voice, a whisper and the ticking of a watch.
Tympanometry examines and diagnoses the middle ear by varying air pressure in the ear canal to see how the ear responds. A probe is inserted into the ear to change the air pressure, produce a tone and measure the responses. The patient may not speak, move or swallow during the test because doing so can affect ear pressure. Tympanometry measures the functionality of the eardrum (tympanic membrane). Abnormal findings may be the result of fluid in the middle ear, a perforated ear drum or impacted ear wax.
Brainstem Auditory Evoked Response Test
The brainstem auditory evoked response test (BAER) examines brain waves that have been stimulated by a clicking sound in order to evaluate the auditory pathways in the brain. Electrodes are placed on the scalp and earlobes, and the patient listens to a clicking noise through headphones. The electrodes record the brain's reaction. The BAER is commonly used to diagnose nervous-system abnormalities and hearing loss in infants and children.
Otoacoustic Emissions Test
Otoacoustic emissions testing (OAE) measures response to sound from the cochlea. The hair cells inside the cochlea vibrate in response to sound. The test is performed by inserting a microphone and two speakers into the ear to emit a sound and then record the response signal. The test is often performed on children when hearing loss is a possibility. Absent or very soft response signals may be the result of hearing loss, fluid behind the ears or damage to the cochlea.
Videonystagmography (VNG) is a test used to record involuntary eye movement called "nystagmus." The test generates nystagmus, and the resulting recorded data determines the vestibular ocular reflex. The VNG is a basic balance test used to diagnose patients with symptoms of dizziness. The VNG is actually composed of seven different tests that help to determine whether dizziness results from a dysfunctions of the ear or from a different factor.
- National Institutes of Health
- Centers for Disease Control and Prevention
- Eunice Kennedy Shriver National Institute of Child Health and Human Development
- U.S. Department of Health & Human Services
- U.S. National Library of Medicine