A hearing exam is the first step in diagnosing a hearing loss. They not only identify that a patient’s hearing is impaired, but they also reveal the type of hearing loss and its severity. Hearing testing evaluates the function of the auditory system including the inner ear and auditory nerve.
There are different test batteries performed depending on the age and development of the patient. Newborns must be tested using strategies that don’t require participation; young children may be best assessed using behavioral tests; adult hearing tests are typically completed using the simplest and most efficient methods available.
Types of Hearing Testing
Auditory Brainstem Response (ABR)
The ABR is frequently used with children and infants. During this test, electrodes are taped to the subject’s ears and forehead, and electrical activity from the auditory nerve to the brainstem is measured. Sounds are presented to the patient’s ears at various pitches, and a sleeping EEG measures the softest sounds detected. ABR tests are performed while patients are sleeping and do not require any response. Once completed, we’ll be able to tell a presence or absence of a hearing loss and, if one is identified, what type of hearing loss it is. This test takes about 30 minutes to complete, though the whole process can take up to two hours.
Otoacoustic Emissions (OAEs)
OAE tests can be used on patients off ages, including infants. They evaluate the function of the inner ear, though they simply identify if it is working and do not measure the amount of hearing. This test can be performed while the subject is awake, but he or she has to be quiet and still. The procedure is painless and takes less than two minutes per ear. If the OAE is the only test completed successfully in a young child, the evaluation will be inconclusive and additional testing will be scheduled.
Tympanometry and Reflexes
This is primarily a testing of middle-ear function to identify a fluid buildup or infection. It can be used for patients of any age. Acoustic reflexes are performed to measure the softest level at which an involuntary reflex occurs in response to loud sounds. Reflex testing, in the presence of normal middle ear function, can help to confirm other test results. The test can be conducted while the subject is either awake or asleep. A probe is placed into the ear while measurements are made. The test is painless and takes less than one minute per ear.
Pure Tone Audiometry
Audiometry testing is completed in a sound test booth. It is generally reserved for teens and adults, and the entire appointment lasts about an hour. You will sit on one side of the booth, while the audiologist is on the other side. You’ll be asked to wear headphones or small foam tips in the ear and use a push button control to indicate when you hear a beeping sound. These sounds are delivered at different frequencies—some low in pitch, others high in pitch—at a very low volume. As you respond, your audiologist will record the lowest level of beeps you hear at each standard frequency. You’ll also listen to beeping sounds while wearing a headband that sits behind his hear, called a bone conduction oscillator. Your audiologist will explain the test results, which are charted on an audiogram.
Speech audiometry tests are also performed in a sound booth. You will be asked to repeat a series of words, which will be delivered at various volumes. When the sound becomes very soft, you may need to guess what is being said.
Behavioral Testing for Children
In additional to pure tone and speech testing, we perform tympanometry, reflexes, and otoacoustic emissions when appropriate. The type of test used depends on the age and development of the child. Tests that are commonly used are as follows:
Conditional Play Audiometry (CPA)
CPA is mostly helpful in testing children ranging from 2–4 years old. Children are taught to perform a simple task (e.g. putting a block in a bucket) every time they hear a sound. Additionally, they may be asked to point to pictures when they hear the corresponding word. A parent can accompany the child into the testing booth. This test requires the use of a trained testing assistant in the booth, as well.
Visual Reinforcement Audiometry (VRA)
This testing technique is used for children 6–24 months old. Children are taught to turn toward a moving toy every time they hear a sound (either speech, noise, or tonal). The child usually sits on a parent’s lap during the testing, and the parent is instructed not to respond to the sounds to avoid inadvertently cueing the child.