Newborn Infant Hearing Screening (cont.)
OAEs and ABRs, is one test better than the other?
Both tests have advantages and disadvantages when used for screening, and
depending on the program and experience of the audiologist, either one can be
utilized successfully. The OAE is easy and cost-effective. However, the
false-positive rate (for example, an infant fails a hearing test but actually has
normal hearing) may be higher for an OAE than for an ABR. The false-positive rate for ABR testing is approximately 4% when testing is done during the first
three days of life. The false positive rate for OAE testing is 5%-21% for testing done during the first
three days of life. This large variation between ABR and OAE testing is commonly felt to reflect the OAE testing device's increased sensitivity to residual amniotic fluid and vernix that is commonly found in the neonate's ear canal.
The two tests,
however, rely on different mechanisms of hearing for the screening. For in-depth
testing and a complete hearing evaluation of infants, these tests work best
together as a complement to each other.
What does it mean when an infant does not pass the hearing screen?
A newborn who fails an initial hearing screen may not necessarily have a
permanent hearing loss or a hearing loss at all. There are many possible reasons
why an infant may fail a hearing screening test. One common reason is that
fluid from the birth may still be present in the ear canal. This fluid blocks
the sound stimulus, preventing it from reaching the inner ear, and therefore
causes the newborn to fail. Similarly, fluid in the middle-ear space behind the
eardrum (a common site for infection in children) can also block the sound
stimulus and lead to a false failed test. After these problems resolve, the
infant usually passes the rescreen. Therefore, it is important to have at least
one week between the initial hearing screen and the rescreen to allow the newborn
a chance to "dry out."
Another possible reason for a false failure is excessive noise or movement
from the infant during the test. The responses that are recorded with an ABR or
OAE are very, very small. Any movement or crying from the infant can prevent the
equipment from detecting the response. Therefore, it is important that the
newborn is quiet or sleeping for the hearing screen. Feeding the infant just
prior to the screening is often very helpful. Although neither test is painful,
they are novel experiences for the newborn and can be momentarily upsetting.
If it becomes evident that an infant has a hearing loss, then a full
diagnostic exam is necessary to determine the type and amount of hearing loss.
Next: What is the difference between a hearing screen and a diagnostic hearing
test? »
- Detecting Hearing Loss in Children - Read about tests used for identifying hearing loss in children, treatment information, causes, risk factors and signs of hearing impairment, and learn about degrees of hearing loss.
- Pregnancy Planning - The goals of pregnancy planning are to create a healthy environment for the fetus and to prevent birth defects and other pregnancy related problems.
- Deafness, Hearing Loss - Hearing loss (deafness) may be present at birth or it may manifest later in life. Deafness may be genetic or due to damage from noise. Treatment of deafness depends upon its cause.
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