On your first visit to an audiologist, he or she will start by asking you questions about your medical and hearing history. This is called the case history. Next, the audiologist will look into your ears using a light, called an otoscope, and check for anything in the ear canal that might affect the test results or require referral to your ENT physician. Finally, the audiologist will conduct a test or series of tests to assess:
- Whether there is a hearing loss
- The cause of the hearing loss (to the extent possible)
- The degree and configuration of hearing loss
- The best treatment options
A hearing evaluation determines the faintest tones a person can hear at selected pitches (frequencies), from low to high. During this test, insert earphones are worn so that information can be obtained for each ear. The person taking the test may be asked to respond to the sounds in a variety of ways, such as raising a hand or pressing a button. Young children are given a more play-like activity to indicate response. The most common techniques involve visual reinforcement audiometry and conditioned play audiometry. The configuration, or shape, of the hearing loss refers to the degree and pattern of hearing loss across frequencies (tones), as illustrated in a graph called an audiogram. The audiogram is a graph showing the results of the evaluation.
The audiologist may also take measurements that will provide information about how the middle ear is functioning. This type of testing is particularly important in preschool children (ages 3–5), for whom hearing loss is more often associated with middle ear disease.
After the test battery is completed, the audiologist will review with you each component of the audiologic evaluation to obtain a profile of hearing abilities and needs. Additional specialized testing may be indicated and recommended based on these initial test results. The hearing evaluation may result in recommendations related to:
- Further follow-up such as medical referral
- Educational referral
- Hearing aid/sensory aid assessment
- Assessment for assistive listening devices
- Hearing rehabilitation assessment
- Speech and language assessment and/or counseling
As you can see, an audiologic evaluation is much more than “just a hearing test!”
Occasionally, further testing may be needed to help identify or confirm specific problems related to the cause of hearing loss or other symptoms associated with hearing loss. An audiologist may perform:
The auditory brainstem response (ABR) test gives information about the inner ear (cochlea) and brain pathways for hearing. This test is also sometimes referred to as auditory evoked potential (AEP). The test can be used with children or others who have a difficult time with conventional behavioral methods of hearing evaluation. An ABR test is often ordered if a newborn fails the hearing screening test given in the hospital shortly after birth, or for older children if there is a suspicion of hearing loss that was not confirmed through behavioral hearing tests. The ABR is also indicated for a person with signs, symptoms, or complaints suggesting a type of hearing loss in the brain or a brain pathway.
The ABR is performed by pasting electrodes on the head—similar to electrodes placed around the heart when an electrocardiogram is run—and recording brain wave activity in response to sound. As sounds are sent through the insert earphones, the electrodes measure how the hearing nerves respond to them. The audiologist looks for certain neurological “markers” in the recorded response. The softest intensity or loudness level at which these markers appear roughly corresponds to the hearing level in that frequency range or pitch. The person being tested rests quietly or sleeps while the test is performed. No response is necessary.
For infants under six months of age, this test can be performed while they sleep in the clinic. For older infants and young children, this test can be performed under anesthesia as an outpatient procedure. This is often done in conjunction with myringotomy and tube placement.
Otoacoustic emissions (OAEs) are sounds given off by the inner ear when the cochlea is stimulated by a sound. When sound stimulates the cochlea, the outer hair cells vibrate. The vibration produces a nearly inaudible sound that echoes back into the middle ear. The sound can be measured with a small probe inserted into the ear canal. The test takes only a few minutes to perform for each ear.
People with normal hearing produce emissions. Those with greater than mild hearing loss do not produce these very soft sounds. This information can be used to (1) screen hearing (particularly in neonates, infants, or individuals with developmental disabilities), (2) partially estimate hearing sensitivity within a limited range, (3) differentiate between the sensory and neural components of sensorineural hearing loss, and (4) test for functional (feigned) hearing loss.