The difference between otoacoustic emissions and automatic auditory brainstem response is a different site of examination, a different principle, and a different primary indication for children. Otoacoustic emissions refer to elastic wave energy from the cochlea recorded from the external auditory canal. The automatic auditory brainstem response is an automated test that stimulates the auditory brainstem with sound and monitors its response. Otoacoustic emission examines cochlear function, such as the outer hair cells of the cochlea, and is a shorter test; the automated auditory brainstem response examines the cochlea, auditory nerve pathways, and brainstem, and is a longer test. Generally newborns are routinely screened for hearing using otoacoustic emission, and children with high risk factors for hearing impairment are screened and further refinement of related tests is done if necessary. However, for example, NICU babies, preterm babies, babies with a family history of hearing impairment, and babies with cytomegalovirus infections are more likely to have an automated auditory brainstem response to avoid missing the diagnosis.