This is a test for a newborn, or for any child or adult who can sleep during the day. The test involves putting three soft recording pads around the head. While sleeping, the audiologist will record the response of the hearing nerve to different levels of sound input and pitches. The results will help determine the sounds that are being detected by the brain, without needing to observe any ‘behavioural’ responses (such as turning to a sound, or pressing a button – which is not always possible to observe/record accurately). This test can take 2-3 hours to complete per session, depending on how long there is restful sleep.