Back in the 1990s, newborns were not routinely screened for hearing problems, which meant the diagnosis of such problems would not take place till the child was a slow to talk toddler.

However, 97% of American babies are screened for hearing problems, while they are still in the newborn nursery. This suggests essential follow-up testing and treatment can begin very early, the key term being follow-up.

According to Marcus Gaffney, a health scientist with the Early Hearing Detection and Intervention program at the Centres for Disease Control and Prevention (CDC), there is no documentation relating to the 46% of children who failed the newborn screening test in 2007, being in for repeat testing and treatment.

As Gaffney says, screening doesn’t help the child, if it is not followed with the appropriate follow-up.

In the late 1990s, newborn screening changed the picture, before which the average age for diagnosing hearing loss was about 2 ½ years of age. And, testing was usually done only because the child’s speech was slow to develop. It sometimes took even longer in those children with relatively mild hearing loss, or loss in only one ear only.

Hearing loss, Dr. Judith E. C. Lieu, a paediatric ear, nose and throat specialist said is hard to spot even in older children, as it may look like they are not paying attention; or they tend to talk while the teacher is talking.

Dr. Lieu is the author of a new study indicating even hearing loss in only one ear results in poorer language skills in children.

One of the most common congenital disabilities affecting 2 to 4 of every 1,000 babies, hearing loss can be genetic, or the result of prenatal infection, the so-called TORCH (toxoplasmosis, rubella, cytomegalovirus, herpes and other) infections that can attack a developing foetus, several of which can damage hearing.

Before the advent of immunization, rubella was a major menace, causing deafness, hearing loss and brain damage. Now, it is cytomegalovirus, a symptomless infection but which can affect a developing foetus, especially if a pregnant woman contracts it in the first trimester. Cytomegalovirus causes severe hearing loss, but which could develop only after the child is born.

Premature babies or those who are ill enough to be placed in the newborn intensive-care unit, also run the risk of hearing loss, either from oxygen deprivation, severe infections or medications.

Then, there are the genetic factors, and hearing loss can be a part of over 400 genetic syndromes.

There are two different technologies for testing a newborn’s hearing, either with otoacoustic emissions, whereby a tiny microphone inserted into the ear of the sleeping newborn measures echoes from the cochlea when stimulated by sound.

Research shows babies that get help by six months have better speech and language development than those identified later.

However, hearing can deteriorate after birth, due to several factors, such as, genetic factors, cytomegalovirus or damage from head trauma, meningitis or exposure to very loud noise.

Any time a parent is concerned about their child’s hearing, they should have it checked.