The mother sits in a soundproof booth with her infant curled up in her
arms. The child has small electrodes taped to her scalp and tiny earphones
placed into her ears. She is set up for a sophisticated hearing test called
an ABR, auditory brain stem response. It looks for abnormalities in an infant's
hearing.
The baby's eyelids are drooping as the mom rocks her, but the baby
still twitches as she settles down for a rest. On the other side of the soundproof
glass, an audiometric technician watches brainwaves dancing across a screen.
He glances up at a video monitor to see when the infant will give in and drift
off to sleep.
In order for this brain stem test to be performed, the child must be fast
asleep. Finally, when the baby closes her eyes and the computer screen reveals
soft loose waves that indicate sleep, the test begins.
"It's important to test all babies for hearing because it can affect
their language development," says Toni Saxton. She is an audiometric technician.
She specializes in testing newborns.
As the child sleeps, sounds ranging from zero decibels to 30 decibels are
run through the earphones. The brain stem response is recorded. If there is
a noticeable dip in the brainwave patterns, the audiometric technician knows
that a sound has been heard.
When the test is complete, the results are passed on to an audiologist
or an ear doctor, who then reads and interprets the results.
Most often, audiometric technicians perform a less complex test that is
done using an infant probe in the ear. "With this screening, the baby is preferably
asleep or resting," says Saxton. This routine test takes five to 20 minutes.
However, the test can take much longer. "You may have to check in with
the mom four or five times before you can take the test," she says. "The mom
might be feeding or the infant might be awake."
Saxton says over the past few years, the hospital where she works has increased
the number of infants that are tested for hearing problems. "Six years ago,
we tested 25 percent and now we're up to 85 percent. It would be more,
but we miss some babies that are born on the weekend."
Saxton enjoys working with children. "It's such a happy time in people's
lives," she says. "It's so enjoyable to be a part of that. For the most
part, you're working with healthy babies."
Of course, not all babies thrive. "We do have to go to the special care
nurseries and in intensive care where the babies are very ill," she says.
"It doesn't happen very often, but the downside of this job is working
with a baby that just isn't doing well."
Children with normal hearing can go on to lose their hearing, especially
if they grow up and work in noisy environments. Many audiometric technicians
work at testing workers exposed to occupational noise.
"Prolonged exposure to noise will cause permanent hearing damage," says
Scott Bradley. He is an associate professor of the occupational hearing conservation
program at the University of Wisconsin. "OSHA [Occupational Safety and Health
Administration] and other federal and state agencies require annual hearing
testing to track workers' hearing."
When a worker is first employed at a job that may expose them to prolonged
sounds over 85 decibels, such as construction work, an audiometric technician
will test their hearing. The softest sound this person can hear is called
their hearing threshold.
Every year, this worker's hearing is retested. If the worker can no
longer hear the softest sound they could hear previously, the audiometric
technician records a threshold shift and hearing loss.
Audiometric technicians hope that no hearing loss has occurred. But if
it has, they can suggest measures to prevent further loss. "There is satisfaction
knowing you're involved in helping to prevent hearing loss in large numbers
of people," says Bradley.
Advances in technology have helped make a technician's work easier.
"Computerized audiometers that allow you to test numerous workers simultaneously
are becoming more popular," he says.
"There has also been some equipment that helps test infants which has been
developed in the last couple of years."
While many of these advances help audiologists, there could be a time when
these advances would help more people work as audiometric technicians. "They
are developing hand-held tests," adds Saxton.
But for now, the infant sleeping in her mother's arms must be tested
while asleep and hooked by wires to computer screens. In this case, the infant
remains asleep and both ears are tested. When the audiometric technician unlatches
the series of soundproof doors and tells the mother the tests are finished
and appear normal, she sighs in relief.
"It's enjoyable to know that you're helping out and that you
can catch problems early so that they cause less problems than they might
in the future," says Saxton.