So, the screening itself is done by a screener in the hospital; all babies are screened within just a few hours of life with either Oto-Acoustic Emissions, in which a small earphone is placed in the babie's ear. with either Oto-Acoustic Emissions, in which a small earphone is placed in the babie's ear. if the ear is healthy, then a sound from that ear-phone is responded to by an echo, or an Oto-Acoustic Emission, that can be measured by this piece of equipment and the result displayed on the screen. 