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NEW HEARING
TEST CAN IMPROVE DIAGNOSIS OF MIDDLE EAR
DISORDERS
Contact:
Andrea Gibson, (740) 597-2166.
SAN
FRANCISCO -- A new test developed by a Nebraska researcher
and studied by scientists at Ohio University could offer
doctors a better diagnostic tool for middle ear infections
and other hearing disorders than currently available
exams.
The
technique, called wide-band reflectance, could help
clinicians understand how middle ear infection, hardening of
the ear bones, facial nerve paralysis or other middle ear
disorders impact a patient's hearing at various
frequencies.
Unlike the
commonly used audiogram, the new technique doesn't rely on
patients to respond to a series of tones. That's a problem
with small children highly prone to middle ear infection who
may be unable to accurately participate in a hearing
test.
In 34
patients with normal hearing, the wide-band reflectance test
detected an acoustic reflex the middle ear's reaction to
loud sounds at least 10 decibels lower on average than the
standard hearing test, says Ohio University audiologist
Patrick Feeney, who presented the study findings Friday at
the American Speech-Language-Hearing Association's annual
convention in San Francisco.
The
findings indicate that doctors can use softer sounds in the
ear canal to make a diagnosis. Some traditional exams may
expose patients to intense noise during testing, which has
reportedly caused hearing loss in rare cases, says Feeney,
an assistant professor of hearing and speech
sciences.
When the
middle ear is exposed to loud sounds, the muscle contracts,
which audiologists believe is a defense mechanism to protect
against hearing damage. When the muscle doesn't contract,
doctors suspect that the patient could be suffering from a
middle ear disorder. "If we can indicate that a person's
reflex is present, it indicates that the middle ear is
working well, that the facial nerve which innervates the
muscle is working and that the person has a functional
hearing nerve," Feeney says.
However,
the traditional clinical exam, which uses a single,
low-frequency 226 hertz tone to gauge the ear's health,
doesn't always offer the whole picture. This test might show
that a patient has no acoustic reflex. But the wide-band
reflectance technique, which measures how the middle ear
reacts to frequencies ranging from 250 hertz to 8,000 hertz,
could show that the ear does have a reflex when measured at
higher frequencies, Feeney says. That could lead to a more
accurate diagnosis of and treatment for the patient's
problem.
Another
advantage to this new technique: A patient complaining of a
middle ear problem might have a normal reading using
conventional tests, but using wide-band reflectance could
confirm the disorder at higher frequencies than detected
through the traditional tympanogram exam.
"The
reflectance technique allows the audiologist to measure the
function of the middle ear over the frequency range
important for hearing speech," he says.
The
wide-band reflectance technique, developed by Douglas Keefe
of the Boys Town National Research Hospital in Omaha, Neb.,
uses a series of eight chirping sounds emitted into the ear
canal to determine how well the middle ear reacts to sounds
that span the human speech range. Computer software analyzes
the data, graphing the middle ear's performance. The
procedure takes only a few seconds.
In the
recent study, Feeney used wide-band reflectance to trigger a
middle ear reaction an average 10.9 decibels lower than the
traditional clinical method. The research grew out of an
initial wide-band reflectance study on three subjects,
published in October in the Journal of
Speech-Language-Hearing Research.
Though
Keefe developed the wide-band reflectance method in 1992,
research into its clinical applications is still under way.
Feeney is using the technique to study patients with otitis
media, or middle ear infections, and to determine what
impact aging has on the middle ear.
The
research on wide-band reflectance was funded by a grant from
the American Speech-Language-Hearing Foundation. Feeney
holds an appointment in the College of Health and Human
Services.
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