Early detection of hearing loss, combined with early intervention, significantly reduces communication delays that commonly accompany hearing loss.

Center for Audiological and Vestibular Services - Audiological Services - Clinical Sensory Physiology Testing

In some cases, behavioral tests cannot provide all of the information needed to diagnose the type, degree, or cause of hearing loss. Specialized electrophysiological tests (similar to an EEG) can be used to help determine what part of the auditory system is damaged or to specify hearing status in patients who are not able to complete standard hearing tests.

The most common of these objective tests is the evoked potential test known as the Auditory Brainstem Response (ABR) test. This test has several applications and is used in the assessment of hearing function in infants, children and adults.

Applications of the ABR test include:

• Newborn Hearing Screening

For infants, the ABR test is often used to screen for hearing loss in the newborn period. The infant sleeps while sounds are played to the ear through a small earphone. Recording electrodes on the head send the response to a computer. Newborn hearing screening also can be performed using otoacoustic emissions (OAE) or a combination of both ABR and OAE measures. Either test can be conducted during the first 24 to 48 hours of life. If the infant does not pass this screening, re-testing should occur as soon as possible. Most infants who do not pass the screening will pass the follow-up test. However, if the follow-up test is not passed, the infant should be scheduled for a diagnostic ABR test.

• Diagnostic ABR Evaluation

This procedure provides an objective test of hearing sensitivity for a range of test frequencies. The test technique is similar to the ABR screening test except that the child must remain quiet for one hour or longer, so a mild sedative may be used for children over 2 months of age. This test can provide information regarding the type, degree, and configuration of hearing loss. When hearing loss exists, the results from this test can be used to select appropriate hearing-aid characteristics for the child.

• Neuro-otologic Examination

This procedure is a specific type of ABR test that provides an assessment of hearing-nerve function. This test is used to screen for certain types of tumors that can occur within the auditory system.

• Electrocochleography (ECoG)

This specialized test is used to assess inner-ear function for patients with dizziness. The procedure is similar to the ABR test, except that electrodes are placed in the ear canals as well as on the head. As with the ABR, sounds are played to the ear as responses are recorded. Results can provide information regarding a possible imbalance of fluids in the inner ear.

• Intraoperative Monitoring

During certain types of ear and skull-based surgeries, evoked-potential techniques may be used to monitor the function of the auditory and/or facial nerve. Continual monitoring during surgery is done to minimize the risk of damage to these nerves.