Newborn hearing testing by Dr.
Christopher Chang of Fauquier ENT of Warrenton, Virginia a newborn hearing screening is performed twenty-four to forty-eight hours after the birth of a child to evaluate for
any type of hearing loss in one type of test, special headphones
are placed over the ears that produce specific
clicks of noise that is then detected by sensors applied as stickers on the forehead as well as near the ear.
These sensors detect nerve signals transmitted from the ear to the brain if no signals are detected the child will fail the hearing test and
hearing loss would be strongly suspected let’s take a closer look and how this
test works known as in auditory brainstem response.
Click noises produced by the test is normally transmitted through the ear
canal to the cochlea and up to the auditory
cortex of the brain if hearing loss is present the signals
will never reach the brain if all goes well however the newborn will pass the hearing test.
It should be kept in mind that approximately two to four babies out of every 1,000 births in the United States are born deaf or hard-of-hearing making hearing
loss the most common birth disorder Although such hearing screening evaluates for significant hearing loss newborns with mild hearing loss may
still pass this test Note on this hearing strange certificate a cut off of 35 decibel hearing
level was used. Auditory brainstem response testing akin to that done in the hospital can
also be performed in specialized hearing centres that often can be found in ENT offices. After
the newborn is comfortably nestled in the mother’s arms the skin over
the forehead and behind the ears are cleaned with alcohol. Sensors are then applied over the forehead and behind the ear. This type of testing done in such outpatient facilities are even more sensitive with sound
levels tested down to as low as 20 decibel hearing level rather than the 35 decibel level cutoff
performed in the hospital. Ear plug headphones are inserted and the
testing has begun. Just as in the hospital newborn hearing
screening, clicks produced by the test can be
traced from the ear all the way to the auditory cortex of
the brain denoted by the squiggles on the screen. There is another type of hearing test
called otoacoustic emissions. This is a much
more basic hearing test were only an earplug headphone is placed. Rather than clicks, this type of testing emits a continuous tone, and if hearing is intact an echo is emitted
by the cochlea hearing organ. This echo is detected by the machine and
displayed indicating the presence of hearing.