Interacoustics AA222 Additional Information page 29

AA222 Additional Information
Peak pressure offset defines how far from the peak pressure the reflex is measured. When multiple
G
peaks are found, the measurement is taken from the highest peak. Note that the automated reflex can
only use the peak pressure when a tympanogram measured at the same frequency precedes the
reflex test.
H Smoothing index allows you to choose the level of detail with which the reflex measurement is
measured and displayed. A smoothing index of 0 means that smoothing is not applied. A smoothing
index of 4 will smooth the curve significantly.
I Checking the Compensate for general drifting option ensures that the base of a reflex sequence
remains at zero even when the probe seal is not completely tight. The compensation takes place just
after a reflex measurement is completed. The reflex graph is then refreshed.
J Measure reflexes at ambient pressure allows you to measure reflexes while the tympanic peak
pressure is being disregarded. When checked, measurements are performed at 0 daPa.
K Pump active between reflexes, when checked, ensures that the pressure is restored to peak
pressure prior to each presentation of the stimulus. When not activated, the pump is used once for
each stimulus type at the start of each reflex sequence.
L Display reflexes as either Positive or Negative makes the reflex curve flip over the x-axis. When
Positive is chosen, you can normally expect the deflection to go in a positive direction. At probe tone
frequencies other than 226 Hz, the compliance is less stiffness-controlled and when measuring an
acoustic reflex it is then not uncommon to measure a negative deflection in adults. Therefore, the
display of reflexes at these probe tone frequencies shows both a positive and negative scale of the y-
axis. Changing this option to Negative will still mirror the graph over its x-axis.
M At Scale you choose the maximum values of the y-axis of the reflex graph. Note that for probe tone
frequencies other than 226 Hz, the scaling is in mmho instead of ml.
When the AGC on stimulus (automatic gain control) checkbox is ticked, the size of the ear canal is
N
taken into account when adjusting the stimulus level. Without compensation, the intensity level will
increase as the size of the ear canal decreases. Note that current tympanometry standards do not yet
describe how AGC should be applied. We recommend that AGC is used when testing infant ears as,
theoretically, with ear canal volumes smaller than 0.2 ml, the stimulus level can be increased by 20 dB
or more. The AGC is applied for both the ipsilateral and contralateral insert.
O The table shows which reflexes will be tested. Selecting the bottom row enables the addition a new
reflex sequence. Hold the
add. Note that rotating down gives ipsilateral stimuli, and rotating up gives contralateral stimuli. The
table below shows which stimuli are available depending on the probe tone frequency and which side
you are measuring. NB stands for narrow band noise. LP stands for low pass filtered noise which has
a spectrum from 400 Hz up to 1600 Hz. HP stands for high pass filtered noise which has a spectrum
from 1600 Hz up to 12 kHz. WBN stands for wideband noise which has a spectrum from 400 Hz up to
12 kHz.
P
To select a reflex sequence from the table, hold the
rotating the wheel. Press the
Q
To select a reflex sequence start level from the table, hold the
wheel to select the desired start level.
R
To select a reflex sequence stop level from the table, hold the
wheel to select the desired stop level. For ipsilateral measurements at some frequencies, the
maximum output is limited compared to contralateral measurements.
button while rotating the wheel to select the stimulus you wish to
button in order to remove the reflex sequence from the table.
button and change the stimulus type by
button while rotating the
button while rotating the
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