MODEL RELEASED. Otoacoustic emission test. Baby with a probe in his ear to test for otoacoustic emissions (OAEs). OAEs are small sounds caused by the movement of the eardrum in response to vibrations from the cochlea. The probe is an ear plug with an earphone and microphone combination. A mild acoustic stimulus is usually given to evoke an OAE, which is measured by a machine (not seen). A healthy cochlea produces vibrations whenever sound is processed, therefore the presence of OAEs indicates normal hearing. An impaired cochlea does not usually produce vibrations, therefore lack of OAEs indicates some degree of hearing loss. This test is for babies only.