Hearing tests are important for your baby

Newborn hearing screening can be conducted in the first days of a baby’s life.
In “well-baby” nurseries this is done via Otoacoustic Emission (OAE) testing.
Babies who are at high risk for hearing loss, or babies who are in the Neonatal ICU (NICU), should be tested with Automated Auditory Brainstem Response testing (AABR) in addition to OAE’s. OAE testing is a fast and effective way to determine the integrity of the cochlea of a baby, as early as 48 hours after birth before discharge from hospital.

AABR is a screening test of auditory nerve function. The baby can be tested after discharge if it wasn’t done in the wards. However it is recommended to be tested in the wards so that the parents don’t forget to have this test done.

How does it work?

A healthy cochlea (part of the inner ear) produces its own sounds in response to incoming sound signals produced by the OAE machine. The cochlea responses are called otoacoustic emissions and are produced by the outer hair cells of the cochlea. An OAE test measures this response. The presence of normal OAE’s can be associated with normal cochlear function. In rare cases cochlear function can be normal but an auditory neuropathy can be present and therefore in high risk cases an AABR should also be performed at birth.

Why should my baby be tested?

Early identification of hearing loss is crucial if children are to learn speech and language. Hearing loss can lead to delayed speech and language development, social problems and academic failure. The hearing screening should be done sooner rather than later as early detection of hearing loss allows for early intervention which is crucial for speech and language development.

Is it painful for the baby?

No. For OAE’s a small probe is inserted in the ear and the baby can even be tested while sleeping. For AABR a small machine is placed on the head and behind the ear.

What does passing these tests mean?

Passing the OAE means that outer hair cells of the cochlear are functioning normally. Passing the AABR means that the auditory nerve pathway is intact and there is no auditory neuropathy. Please remember that the baby may get ear infections/diseases at a later stage, which can affect the hearing. We therefore advise that the baby be tested in 6-12 months’ time, for a routine follow-up. Any changes in a baby’s response to sound should be monitored.
What if my baby does not pass the hearing screening?

If your baby does not pass the hearing screening at birth, it does not necessarily mean that your baby has a hearing loss. But to be sure, it is extremely important to have further testing.

Two reasons for not passing a new born hearing screening test are possible:

1. There is a temporary obstruction or hearing loss. Either the baby has still has amniotic fluid present in the ear canal, or fluid in the middle ear/ear canal which prevents the sound from reaching the cochlea. In this case the baby will be retested in 2-6 weeks time and usually a pass will be obtained at the second test.

2. There is permanent damage in the cochlea that the baby was born with (congenital hearing loss). This means that even a test repeated in two to six weeks’ time will not yield a pass.

If your baby fails the first hearing screening, he/she should be re-tested in two to six weeks’ time before a diagnosis will be made. If there is fluid in the middle ear the baby is sent to an Ear Nose and Throat Surgeon (ENT) for further management of the ear canal and middle ear. Once the ENT has resolved the middle ear pathology, the baby is retested. If the baby does not pass the OAE’s a further battery of hearing tests is done to determine if the baby presents with a congenital hearing loss. This involves a more thorough hearing test and a medical evaluation. These tests should be done as soon as possible, but definitely before your baby is 3 months old.

If a permanent congenital hearing loss is found, what can be done?
This depends on the type and degree of hearing loss that your baby has. Every baby with hearing loss should be seen by an audiologist and an ENT. If the hearing loss is permanent, hearing aids and speech and language services will be recommended for your baby. For certain types of hearing loss, surgical procedures may be done. Cochlear implants may be recommended if the hearing loss is profound and a hearing aid trial period has been done. Some children with hearing loss can also have problems with their vision and should therefore be tested by an ophthalmologist. Many children are also seen by a geneticist to determine if there is a hereditary cause of hearing loss.

HEARCARE WATERFALL- Hearing and Balance Clinic
TALIA ARONOWITZ
Speech-Language Therapist & Audiologist
B.A.(Sp & Aud.)(Wits)(Cum Laude)
Newborn hearing screening can be conducted at the HearCare Mulbarton Hearing and Balance Clinic which is situated at Netcare Mulbarton Hospital (011 682 1585).