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The pressure sweep begins at the starting pressure of +200 daPa and proceeds in the negative
direction at a rate of 600 daPa/second. Measurements of compliance are made continuously
as the pressure sweep continues in the negative direction. The slope of the tympanogram
increases as the measurement approaches the compliance peak. This signals the instrument
to decrease the rate of pressure sweep to 200 daPa/second to ensure a more accurate reading
of the compliance peak. After the peak compliance and pressure values are detected and
stored, the tympanogram dips downward toward the baseline (i.e., 0 cm
3
) and the pressure
sweep rate increases back to 600 daPa/second. The tympanogram sweep ends automatically
when the compliance value returns to baseline and the pressure is at least -100 daPa. Only
when the middle-ear pressure is very negative is it necessary for the pressure sweep to
continue to -400 daPa. The automatic stop when the tympanogram compliance returns to
baseline eliminates unnecessary pressurization of the ear and shortens the test time.
When the tympanogram is completed and the test is finished, the steady green lamp turns off
and the test results are displayed.
For the 1000 Hz probe tone, the measurement taken at +200 daPa will be identified as C1 and will
not be a calculated volume. For the 1000 Hz probe tone, the default setting for Auto Start is turned
off. This setting is recommended to ensure the probe is placed properly in the ear
canal prior to testing. To begin the pressure sweep, press the button.
The pressure sweep rate of 200 daPa/second remains steady through the peak measurement and
will continue to -400 daPa. The green lamp will turn off when the test is completed.
The test results are stored automatically in memory. The actual memory location number is
determined by the number of tests that are stored. For example, if this is the first test to be stored
in memory, it will be assigned the number Ml. If it is the third test to be stored in memory, it will
be numbered M3, etc.
In addition to the tympanogram tracing, the screen displays the test summary information. For
226 Hz probe tones, this data includes the ear canal volume (ECV), the compliance peak in cm
3
,
the pressure at the peak of the tympanogram indaPa, and the gradient (GR) as a peak width value.
This test result can be printed out immediately as a single test by selecting the Print Screen Only
button or other tests can be performed and saved before all tests in memory are printed via
the Print All button. For 1000 Hz probe tones, the data accompanying the tympanogram will
include a C1 value (in mmhos), a mmho compensated peak value (Peak - C1 = compensated peak
in mmhos), and Peak Pressure in daPas.
NOTE:
If a second tympanogram needs to be performed for 226 Hz, remove the probe and reinsert
the probe. If Autostart is turned off on the 1000 Hz test, the probe does not need to be removed
to run a second tympanogram. Press the button to start a 2
nd
measurement. If the pump
cannot run a 2nd tympanogram due to pressure equalization,
remove
will appear on the bottom
right of the LCD. Remove the probe and reinsert for the next tympanogram.
