What is Auditory Brainstem Response (ABR) testing?

Auditory Brainstem Response (ABR) Testing evaluates how the nervous system, specifically the brainstem, responds to specific sounds. During an ABR test, electrodes are attached to the patients scalp. Earphones placed in the patient’s ears deliver a series of tones or clicks to each ear separately. The electrodes record the electrical responses from the patient’s brainstem and these responses are recorded by a special computer.

What does an ABR assess?

ABR tests are used to evaluate acoustic neuromas, brain stem tumors, hearing disorders, comas, brain death, and demyelinating diseases such as Multiple Sclerosis. They are also used to evaluate hearing loss in infants, small children and other patients unable to give voluntary subjective responses to traditional hearing tests. For some infants and children behavioral testing does not provide reliable results. In such cases, an ABR test may be recommended. The ABR test can provide useful information about the type and amount of hearing loss, the effect on communication abilities, and the functioning of the hearing nerve.

Otoacoustic Emissions

An Otoacousitic Emission (OAE) is the response the ear makes to sound. OAEs are produced by the activity of tiny hair cells located in the cochlea.

How are OAEs measured?

OAEs are measured by presenting a series of tones or clicks to the ear through a small probe inserted into the ear canal. The probe contains tiny speakers and a microphone. The tones or clicks are presented to the ear through the speakers. When the ear hears these tones or clicks it causes little hair cells in the cochlea to move and produce an echo. This echo, or OAE, is picked up and measured by the microphone.

Why are OAEs important?

OAEs only occur in a normal cochlea with normal hearing. If there is damage to the outer hair cells producing a mild hearing loss, OAEs are not present.  OAEs are present only if hearing is 35 dB or better. OAEs can provide information on the frequency range from 500-8000 HZ. They are appropriate for use in difficult to test patients: newborn infants, young children, and developmentally delayed persons. OAEs only provide information about the activity of the cochlea and do not assess the status of the auditory pathway, which is tested by the Auditory Brainstem Response.