Page 49 of 112
TYMPANOMETRY AND CONTRALATERAL REFLEX (VERSION 2 AND VERSION 3)
To select tympanometry and contralateral reflex testing:
1.
Press the
Tymp Reflex
mode button. This initializes the GSI 39 to perform a
tympanogram along with reflex measurements. The factory default setting for reflexes is 1000
Hz Ipsilateral presentation.
2.
To temporarily change the system to perform Contralateral Reflexes only, you first deselect
the 1000 Hz Ipsilateral. To deselect the 1000 Hz IPSILATERAL, simply press the
1000 HZ
button,
“
1
000” should no longer
be displayed on the right side of the LCD.
3.
Press the
CONTRA
CONTRA
button. This displays the letter
C
in front of the frequency labels.
4.
Select the test frequencies by pressing the desired Frequency button (e.g.,
500 HZ
or
1000 HZ
).
Pressing the Frequency button a second time will deselect that frequency from the test
sequence. Test frequencies must be selected before the probe is in the ear canal.
5.
Before initiating this test sequence, select the appropriate
size eartip
for the contralateral
insert phone from the color-coded eartip container. The insert phone should fit snugly in the
ear canal.
6.
Push the selected eartip firmly onto the insert phone. Be sure to carefully position the insert
phone within the ear canal as the calibration depends upon a proper seal of the ear canal.
7.
Select the test ear by pressing
R
or
L
. According to general convention for recording
contralateral reflexes, the test ear is the ear where the probe is positioned and the stimulus
ear is the ear that contains the contralateral insert phone. If the contralateral insert phone is
placed in the left ear, the test ear is the right ear since this is the ear from which the reflex
response is to be measured. Press the button that corresponds to the ear with the probe to
select the test ear.
To initiate the test:
1.
Position the insert phone securely within the ear canal to receive the contralateral stimulus.
2.
Position the probe into the ear canal of the test ear. Note that the green lamp changes from
a blinking to a steady state when the test begins.
3.
Monitor the probe and the ear canal throughout the test sequence. The test begins with the
tympanogram and is followed immediately by the contralateral acoustic reflex test.
For
226 Hz Probe Tone
, the pressure value used within the test ear throughout the
contralateral stimulus presentations is the peak pressure obtained during the tympanogram
offset by -20 daPa (+20 daPa if peak pressure is positive).
For
226 Hz Probe Tone
, a compliance change of 0.05 cm
3
indicates a reflex response. Up to
three intensity levels per frequency selected are presented. The format in which the test
results are displayed on the screen is determined by the default setting chosen in the Program
mode (i.e., yes/no, dB HL, or dB HL and response curve). The three intensity levels available
per frequency are the same for all four (500, 1000, 2000, and 4000 Hz) possible frequencies,
90, 100, and 110 dB HL.