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(d) The patient is prompted to pronounce a sustained vowel and at the same time
the foot is eased upwards to the mechanical stop of the pedal. A stroboscopic
light is, thereby, produced to show the motion of the vocal cords at a slow
motion frequency of approx. 1,4 Hz with an apparent motion sequence equal to
that of the real motion which appears at the voice frequency. A study of the
details in the motion is thereby possible. The Display shows the voice frequen-
cy. See Fig. 3.12.
Voice Frequency, Hz
Trigger
Phase,
0
Fig. 3.12.
5.
For some investigations it is of interest to know the relative duration of different
parts of the glottal function. For this purpose the pedal may be released beyond its
stop into the variable phase region. In this region, a sustained vowel from the pa-
tient produces a "frozen" stroboscopic picture of the vocal cords. The picture may
be chosen at any part of the motion sequence and the relative phase of each setting
may be read-off from the Display in 10° steps. See Fig. 3.13.
Voice Frequency, Hz
Trigger Phase,
0
Fig. 3.13.
6.
By totally releasing the Pedal, the Stroboscope Lamp will stop operation and the
instrument will return to the "FILTER READY" position. It is now possible to start a
new examination sequence (see point 3. or point 4.).
3.7.
CLEANING AND DISINFECTION
14
1.
The instrument itself, the Cable Lifter and the Pedal may be cleaned by wiping them
with a tightly wrung cloth using a solution of mild detergent. Care should be taken
not to wet the cables, plugs and sockets.
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