How Do You Know if Your Child Has a Hearing Problem?
Hearing is the first sense to develop. The growing and developing fetus in the mother’s womb has been found to respond to sounds, especially its mother’s voice. The fetus moves in response to sounds from the outside. It is joyful and happy when the sounds outside are happy and the growing fetus gets stressed out if the sounds are angry, sudden and violent.
The doctor will take a detailed history of the mother’s pregnancy noting if there were any problems during pregnancy such as if the mother had measles, rubella, mumps etc. These illnesses can most likely have a negative impact of the fetus’s hearing.
When the baby is born it is very important to know if the new born can hear well. Since the new born baby is unable to speak it is important to use methods that are reliable, verifiable and accurate to identify if the baby can hear or not.
The first basic and simplest test is the startle reflex. If the new born does not get startled if there is a sudden noise then it is likely that the child may have a hearing impediment.
The ENT doctor will examine the child’s ear to check if there are any obvious problems. It is unlikely that the newborn will have impacted wax in its ears. But whatever debris is there in the external canal is removed.
The newborn can undergo a test known as "Otoacoustic emission (OAE)” audiometry. This is an objective test that is reliable and can be repeated. This test can be conducted at the newborns bedside and is painless. The test takes a few minutes. This tests the hair cells of the cochlea that is found in the inner ear. This test requires the child to be still (and not crying) and that the room should be quiet. If the child fails the test the test should be repeated again the next day. Failing the test could also be the result of amniotic fluid still residing in the child’s external ear.
Brainstem Evoked Response Audiometry (BERA) Also Known as ABR – Auditory Brainstem Response Audiometry.This is another computerized hearing test. It tests the integrity of the auditory pathway from the inner ear to the brainstem. This test is an objective test and is painless and takes about 15 minutes to do. It has a 96% accuracy. Both the OAE and the BERA are tests used in all modern hospitals to evaluate a newborn child hearing.
If the Child Gets a Failed Test, Then What Next?The OAE has an accuracy of 90% while that of the BERA is 96%. Both tests should be done together. If the child fails both the tests then both the tests need to be repeated the next day to check the child’s hearing again. It is possible for the child to have normal hearing at the second test. This is because of vestigial remnants of amniotic fluid in the external ear canal and other variables like the child being restless during the first test, ambient noise in the room that has interfered with the test etc.
Which Test Should be Done, OAE or BERA?Both tests should be done as they both test different aspects of hearing and the auditory nerve and inner ear. Both are standard, routine tests and can be done in most hospitals.
Impedance (Immitance) Audiometry.
This test is also a subjective test and determines the status of the middle ear cavity. Sometimes fluid can be trapped in the middle ear cavity. This can impair hearing. This test is painless and is computerized.
The ENT doctor puts together the events of pregnancy, the birth process, clinical examination and the findings of the OAE, BERA and Impedance audiometry before deciding what the course of treatment should be.
All new born infants should undergo OAE and BERA to determine the status of their hearing even if the pregnancy and delivery was safe and uneventful.