Most often, the parents are the first to detect hearing loss in their child. Unfortunately, many children with severe hearing loss from birth are not diagnosed until 2 1/2 or 3 years of age.
(inner and middle ear of baby-3D CT Scan)
Hearing loss can be categorized by many different types. Two types of hearing loss are sensorineural and conductive. Both types of hearing loss can be congenital (present at birth) or acquired.
Without screening or testing, hearing loss may not be noticed until the baby is more than 1 year old.
If hearing loss is not detected until later years, there will not be stimulation of the brain’s hearing centers. This can affect the maturation and development of hearing, and can delay speech and language. Social and emotional development and success in school may also be affected.
Many hospitals automatically screen all newborns for hearing loss. Some screen only those newborns at high risk for hearing loss, such as babies with a family history of deafness or hearing problems, low birth weight, or certain other medical conditions.
Its is estimated that one to two new babies in every 1000 born will have some level of hearing loss in one or both ears.
Screening test in new born babies
Two hearing tests are used to screen babies.
and Otoacoustic emissions (OAE)
and Auditory brain stem response (ABR)
Otoacoustic emission test -OAE
Otoacoustic emission test is a test performed for recording a sound produced by ear.
In 1978, Kemp from UK reported otoacoustic emissions for the first time.
The health of inner ear is measured with the help of this test.
The test is performed by placing a small probe that contains a microphone and speaker into the infant’s ear. As the infant rests quietly, sounds are generated in the probe and responses that come back from the cochlea are recorded. Once the cochlea processes the sound, an electrical stimulus is sent to the brainstem. In addition, there is a second and separate sound that does not travel up the nerve, but comes back out into the infant’s ear canal. This “byproduct” is the otoacoustic emission. The emission is then recorded with the microphone probe and recorded on a computer screen. The audiologist can determine which sounds yielded a response/emission and the strength of those responses.
In otoacoustic emission test, if the microphone is able to detect the emissions from the inner ear then it is considered to be normal (pass). The results are considered as abnormal if no emissions are observed during the test.
It is noninvasive test. The test is performed on newborns or babies who cannot cooperate during conversational tests as being too young.
If the baby has recent cold, ear infection or wax in the ear it can adversely affect the test. Also difficult to do it kids who has narrow collapsed ear canal.
Pass or Refer(? fail)
The test can be repeated in case of refer(fail).Babies who do not show strong responses to the two screening tests will be referred on for a full diagnostic assessment of the hearing. This will be done at ENT Department.
Auditory brain stem response (ABR)
ABR-tests check how the brain stem (the part of the nerve that carries sound from the ear to the brain) and the brain respond to sound. During this test, your child wears earphones, and electrodes are placed on the head and ears. A mild sedative may be given to help keep your child calm and quiet during the test. The nurse or doctor sends sounds through the earphones and measures the electrical activity in your child’s brain when he or she should be hearing.
For further information-
Please contact the ENT department or the Pediatric development department at the SUT Hospital.