The Oto-acoustic emissions is a test used to measure hearing loss.

OAEs test the outer hair cells in the cochlea, which is responsible for relaying sounds to the brain. This test is a quick and easy way to test the functioning of the hair cells and can even be done on new-born babies. During this test, the patient and the environment must be quiet, as noise can interfere with the results. A small probe is inserted in the ear canal and different sounds are played through the probe for the patient to hear. It only takes a minute or two and the patient does not need to respond to the sounds as the response is recorded automatically. This test will indicate whether there is damage to the cochlea, which would indicate a hearing loss. Some patients may have normal OAEs, but still have a hearing loss, which will then indicate that the damage is further in the acoustic chain, for example in the hearing nerve or the brainstem.