Today, most babies' hearing is screened quickly after they are born. Not all babies pass the hearing screening the first time. Failing the screening does not automatically mean the baby has a hearing loss. Babies who do not pass the first hearing screening are typically given a second screening to be sure of the findings.
Here's a quick informative video about infant hearing screenings:
The two most common screening methods used are otoacoustic emissions (OAEs) and auditory brainstem response (ABR). Both are quick and painless. They are usually done while the babies are sleeping.
OAEs can detect blockage in the outer ear canal, as well as the presence of fluid in the middle ear and damage to the outer hair cells in the cochlea. When used as a hearing screening, ABR tests only one intensity or loudness level. As with most screening measures, the baby either passes or fails the screening.
I couldn't resist the urge to include this video of this adorable baby boy who was 7 weeks old when he received his first hearing aids. Look at his cute smile after hearing sound probably for the first time.