The Importance of Hearing Screening
Hearing loss in newborns is a common problem in developing countries, causing impairments in communication. Language and speech development are significantly delayed compared to normal children.
Incidence
Thailand has reported an incidence rate of hearing loss of 1.7 cases per 1000 newborns per year. When separated into groups, normal newborns have an incidence of 1.3 cases per 1000 newborns per year, while high-risk newborns in neonatal intensive care units have an incidence of 15.3 cases per 1000 newborns per year.
Otoacoustic Emissions (OAEs) Test
This test evaluates the function of the outer hair cells located inside the cochlea by measuring the sound energy that is reflected back. The measurement can be recorded in the external auditory canal. The test can be performed while the child is asleep. The examiner inserts a probe that fits the child’s external auditory canal, emits sounds to stimulate, and records the response.
Interpretation of Screening Results
It should be understood that screening is not a diagnostic test but a method to broadly identify children who may have a risk of disease for further detailed diagnostic examination.
If the screening result is failed, it does not mean the infant has hearing loss until a detailed diagnostic test is performed. A failed screening result may be due to earwax or fluid in the ear canal, earwax blockage, or fluid in the middle ear, which are common in normal children. If treated or if these conditions resolve, the screening result often passes later on.
However, even if the newborn hearing screening result is initially passed, it cannot guarantee that there will be no hearing loss later (progressive hearing loss), which may be caused by abnormalities in the auditory nerve system (sensorineural hearing loss) or other genetic disorders. Therefore, parents should be knowledgeable about the infant’s language and speech development to monitor this development periodically. If any abnormalities occur at any stage, they should return to see a doctor, specialist, audiologist, or speech therapist until the child’s language and speech are comparable to normal children.
