Definition and Overview

Hearing tests, also called as audiometric tests, examine a person’s ability to transfer external sounds to the brain. Vibrations in the environment produce sound waves, which are measured in frequency (pitch) and amplitude (volume). The sound waves travel through the ear and are converted into impulses, which are then transmitted to the brain. The brain will then process the impulses thus completing the “hearing process.” Hearing tests determine if there are any obstructions anywhere in the process.

Types of hearing tests

Doctors, audiologists, and ENT specialists perform hearing tests through several different methods. The tests will determine the type of hearing problem whether it is conductive, sensorineural or neural.

  • Conductive hearing problems indicate that sound waves do not pass through to the inner ear, which could be caused by blockage in the outer or middle ear.
  • Sensorineural hearing problems indicate that the nerves in the inner ear are unable to process or transmit the information to the brain.
  • Neural hearing problems indicate that the brain is unable to process the impulses transmitted by the inner ear.

Below are some of the most common hearing tests

Weber and Rinne Test – This type of test determines if there is a conductive or sensorineural hearing problem. The doctor will place a tuning fork at the back of the ear, near the mastoid bone (bone conduction). The doctor will then strike the fork and record the time it takes until the patient can no longer hear the sound. The fork is then moved to the outer ear, near the ear canal. The doctor will repeat the process and record the time it takes until the patient can no longer hear the sound or vibration (air conduction). The doctor will then compare the time difference between bone conduction and air conduction. The fork is then moved to the forehead, and the doctor will ask whether the left, right or both ears are hearing the sound.

The results of Weber and Rinne Test are interpreted as follows:

The result of the air conduction test should be twice as long as the bone conduction test. If the bone conduction test is equal or longer than the air conduction test, the patient is likely experiencing conductive hearing loss.

If the result of the air conduction test is longer but not twice as long as the conduction test, there is a high possibility that the patient is experiencing a sensorineural hearing loss.

When the fork is transferred to the middle of the forehead, the patient should hear the sound in both ears. In conductive hearing loss, the sound will travel to the poor ear. In a sensorineural hearing loss, the sound will travel to the good ear.

Hearing in Noise Test (HINT) – This type of test will determine the patient’s ability to hear speech in a quiet and noisy environment. The patient is asked to repeat a sentence, first in a quiet environment. Noise is then introduced, and the sentence is played from four locations: front, 90 degrees to the right, 90 degrees to the left, and from the back of the patient’s head. The volume of the sentences is increased and decreased to determine how loud they need to be played so that the patient can correctly repeat the sentence at least 50 percent of the time.

Tympanogram – In this test, the doctor will insert a small probe inside the ear. Pressure inside the ear canal is then varied, and the probe will determine how well the eardrum and other structures in the ear respond. This test can determine if there is a perforation in the eardrum or if there are fluids present in the middle ear.

Acoustic Reflex Test – In this test, a probe is inserted into the ear canal and a loud sound is introduced. The test will determine the hearing thresholds of a patient.

Who needs to undergo hearing tests?

  • Babies and young children to determine if their speech or learning abilities are due to a hearing problem.
  • Children and teens should also undergo hearing tests to check for any hearing loss.
  • Anyone who has noticed a decrease in hearing abilities.
  • Older patients who do not respond to conversations.
  • People who are often exposed to loud noises.
  • People who experienced decreased hearing after a cold or infection.

If hearing loss is determined, the doctor will decide on the best method of treatment. Treatment for hearing problems can include medications or even surgery.

References:

  • Hearing Screening and Testing. American Speech-Language Hearing Association
  • Hearing: Screening and Diagnosis: Centers for Disease Control and Prevention
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