One or two babies in every 1000 babies have permanent hearing loss in either one or both ears. There are certain factors which increase the risk of hearing the loss in newborn. The factors include:
- Illness of mother during pregnancy
- Family history of hearing loss
- Exposed to certain drugs which affect hearing
Baby’s development is affected significantly due to permanent hearing loss. Early detection of hearing loss in a newborn can help these babies to develop language, speech and communication skills.
Hearing screening test should be done in infants with the following conditions:
- Low birth weight/premature birth / Lack of oxygen or breathing problems at birth
- High bilirubin levels (Jaundice)
- Syndromes correlated with hearing loss
- Abnormal head or face structures
- Long time in mechanical ventilation
- Infections such as Cytomegalovirus, syphilis, herpes or toxoplasmosis.
There are two different methods to test hearing loss in infants, and they are the automated auditory brainstem response (AABR) evaluations and the automated otoacoustic emission (AOAE) measures.
AOAE Test: Duration of the test is just a few minutes. A small soft-tipped earpiece is kept in the baby’s ear, and gentle clicking sounds are played. The inner part of the ear gives response after the ear receives sound. Then screening equipment picks up the sound. The first test may not be successful all the time. The test results mean:
- the baby was unsettled during the test
- background noise was present
- Baby has fluid or a temporary blockage in their ear
AABR Test: Another hearing test, AABR test is also conducted to detect hearing loss in newborn. Three small sensors are placed on the baby’s head and neck. Now soft headphones are kept over baby’s ears, and gentle clicking sounds are played. Duration of this test is between 5 to 15 minutes.
These hearing tests are not harmful to the newborn babies. AOAE and AABR tests are accurate, noninvasive, automated and it is not necessary to receive any observable response from the infant during these tests. The AOAE test is easy and costs effective compared to ABAR test.
If a newborn fails in the initial hearing screen test, it does not mean that the baby has a permanent hearing loss. Following reasons could be responsible for the failure of a hearing screening test:
- Presence of fluid inside the baby’s ear canal
- Presence of background noise
- Movement of the infant
The result of the hearing test is given immediately after the test. These screening tests do not pick up all types of permanent hearing loss. Sometimes children develop permanent hearing loss later. Hence it is important to monitor child’s hearing once they grow up.