Parents should be sure to ask the doctor about getting a newborn hearing screening test. It’s best to have it done in the hospital, but if it’s not available there, be sure to have it done by your doctor or a hearing specialist before your baby is three months old.
If the results are not normal, special services are provided to your baby and the family. If a hearing problem is diagnosed early, and treatment started right away, a baby is far more likely to have normal language skills. If hearing loss is not found and helped until later, the child is more likely to have serious language and communication problems.
—- from First5 Advice for New Parents