during this check as mechanical noise may be picked up by the probe and
interfere with the calibration check.
The calibration check will start automatically after the Start button has been
pressed if the probe has been inserted into the cavity properly. This is confirmed
by the green lamp changing from blinking to a steady condition. If the orange
lamp is illuminated, the probe is not properly positioned within the cavity so that
a large pressure leak exists. If the yellow lamp is illuminated, the probe tip has
been occluded. In either case, remove the probe and wait for the blinking green
lamp. Insert the probe once again. If necessary, clean the probe tip as described
later in this chapter.
The green lamp will resume blinking when the probe is removed from the test
cavity. The tympanogram on the display represents the response from the 0.5 cm
3
hard walled cavity. The Vea (acoustic equivalent volume) should read 0.5. The
letters NP will appear alongside the pressure (daPa) and compliance (mmho).
Using the same sequence, place the probe in the test cavity opening labeled 2.0
cm
3
. The resulting tympanogram should be identical other than the Vea should
read 2.0 cm
3
.
The same sequence may be followed with the 5.0cm
3
opening on
the test cavity. Keep a copy of the tests for a day-to-day reference in checking
the instrument.
Since sound pressure will vary with altitude and barometric pressure, some
variation from the 0.5, 2.0 and 5.0 cm
3
readings may be observed. The
instrument is carefully calibrated at the factory, which is at approximately 850
feet above sea level. At an elevation of 1500 feet or higher, the instrument may
need to be recalibrated to account for elevation. It is not necessary to recalibrate
for barometric pressure changes on a daily basis. Keep in mind that a change in
barometric pressure (i.e., from low to high or vice-versa) will slightly affect the
test cavity readings.
678 Hz and 1000 Hz
To initiate the quick check for the 678 Hz and 1000 Hz probe tone, select the
Tymp button on the front panel and the appropriate probe tone frequency from
the Tymp parameter from the Tymp menu. Follow the same procedure as
describe for the 226 Hz probe tone. Note however that the 5.0 cm
3
is beyond the
measurement capability of the 1000 Hz probe tone and therefore no need to test.
If you test the 1000 Hz probe tone in the 5.0 cm
3
cavity you will receive a leak
detected error message.
Summary of Contents for TYMPSTAR PRO
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