OTOACOUSTIC EMISSIONS (OAE)
Otoacoustic Emissions OAE testing provides information about how the hair cells of the cochlea are working by measuring the responsiveness of hair cells to a series of clicks produced by a tiny speaker inserted into the ear canal. Most often Otoacoustic Emissions test is used to evaluate hearing for people who are unable to respond to a traditional hearing test (such as infants).
ECoG measures a response to sound from the nervous system. An earphone plays sound in the ear and an electrode measures a response. Different electrodes can be used in this test. Some may be adhesive, skin-surface electrodes. Others may fit in the ear canal like an earphone, while a third type of electrode is designed to gently rest against or touch the eardrum. A fourth type of electrode is a needle that is placed through the eardrum to touch the inner ear. Most clinics use the first three types of electrodes to measure an electrical signal while sound is playing.
AUDITORY BRAINSTEM RESPONSE TEST (ABR OR BER OR BAER)
The ABR measures how the nervous system responds to sound. The test setup and procedure is similar to the ECoG. Most often ABR is used to test hearing for people who are unable to respond for audiometry (such as infants). Under certain circumstances, this test can indicate the presence of an acoustic neuroma (a rare, benign tumor of the vestibulo-cochlear nerve). It may also help identify conditions such as multiple sclerosis if they have affected the auditory pathway to the brain.