When the test result is “NOISY,” “NO SEAL,” or “FIT ERR,” the
tester should reposition the probe, selecting a different size eartip if
necessary, and retest. To review the results, push the
DOWN arrow
key to return to the bar graph (Display 8). After reviewing the results,
again push the DOWN arrow key to return to the Results display
(Display 11 or Display 12
)
or the up arrow to return to the Main Menu
(Display 1).
NOTE:
Completed tests are automatically saved. By default (Save
L/R Mode), the Corti instrument will save only the last test for each
ear. Starting a new test for the same ear will overwrite the existing
test.
See the next section
Managing Test Results
for more information on
how the Corti saves results and how to print or transfer those results
to the Corti Data Manager.
See the section
Instrument Settings - Save Mode
on page 32 or more
information on the Corti save mode options
.
Viewing DPOAE Results with Normative Data
The Corti will display the Expanded Boys Town Norms
template
for eligible DPOAE test results. The norms template has no effect
on the overall test results and is for display purposes only. The
values used to create the template are shown in Table A1 from
Gorga, M.P., Neely, S.T., Ohlrich, B., Hoover, B., Redner, J. and
Peters, J. (1997). “From laboratory to clinic: a large scale study of
distortion product otoacoustic emissions in ears with normal hearing
and ears with hearing loss.” Ear & Hearing, 18, 440-455.
The template may be used as a guide when evaluating DPOAE test
results. The light shaded area at the top of the template represents
the 90
th
to 95
th
percentile of DP amplitudes from the hearing
impaired population. DP amplitudes within or above this range
indicate a high probability of normal hearing. The light shaded area
at the bottom of the template represents the 5
th
to 10
th
percentile of
DP amplitudes from the normal hearing population. DP amplitudes
within or below this range indicate a high probability of hearing
loss. The dark shaded area in between represents a range of
uncertainty where the normal hearing and hearing impaired
populations overlap.
Test Technique
As with other otoacoustic emission test instruments, there is a
technique to learn when using the Corti instrument, especially while
testing infants. Experience with existing OAE systems suggests that
it may take up to 3 months to become completely proficient at
screening infants.
When testing an infant with the Corti instrument, the infant has to be
relatively quiet and calm; it is usually preferred for the infant to be
