Interacoustics AT235 Additional Information

AT235 Additional Information Page 18
E
Probe tone frequency. The frequencies which can be selected are 226Hz (recommended for
normal testing), 678Hz, 800Hz and 1000Hz.
.
F
The Peak pressure offset defines how far from the peak pressure the reflex is measured. When
multiple peaks are found, the measurement will be 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.
G
The 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 be applied. A
smoothing index of 4 will smooth the curve significantly.
H
Checking the Compensate for general drifting option will ensure that the base of a reflex
sequence will stay at zero even when the probe seal is not completely tight. The compensation
takes place just after a reflex measurement is finished. The reflex graph is then refreshed.
I
Measure reflexes at ambient pressure allows you to measure reflexes while the tympanic peak
pressure is being ignored. When checked, measurements are performed at 0 daPa.
J
Pump active between reflexes will, when checked, make sure that the pressure is restored to
peak pressure before each presentation of the stimulus. When not activated, the pump is used
once for each stimulus type at the start of each reflex sequence.
.
K
Display reflexes as either Positive or Negative makes the reflex curve flip over the x-axis. When
Positive is chosen, you will 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 those probe tone frequencies shows both a positive and
negative scale of the y-axis. Changing this option into Negative will still mirror the graph over its x-
axis.
L
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.
M
When the AGC (automatic gain control) checkbox is marked, the size of the ear canal is 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.
.
N
The table shows which reflexes will be tested. Selecting the bottom row allows for adding a new
reflex sequence. Hold the button while selecting with the wheel the stimulus to
be added. Note that rotating down gives ipsilateral stimuli and rotating up gives contra lateral
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.
O
To select a reflex sequence from the table, hold the button and change the
stimulus type by rotating the wheel type. Press the button in order to remove the
reflex sequence from the table.
P
To select a reflex sequence from the table, hold the button while rotating the
wheel for selecting the wanted start level.

Interacoustics AT235 Specifications

General

Brand	Interacoustics
Model	AT235
Category	Measuring Instruments
Language	English