Interacoustics AT235 Installation manual

D-0105061-D – 2017/05
Additional Information
AT235
Impedance Audiometer

Table of contents
1AT235 Tympanometry Module ........................................................................................................ 1
1.1 About the AT235 Tympanometry Module........................................................................... 1
1.2 Preparing for the Test......................................................................................................... 1
1.2.1 Tympanometry patient instruction.......................................................................... 1
1.2.2 Visual inspection of the ear canal.......................................................................... 1
1.2.1 Placement of the contralateral phones .................................................................. 2
2General Operation of the AT235 Tympano-metry Module.............................................................. 3
2.1 Tympanometry.................................................................................................................... 3
2.2 Reflex.................................................................................................................................. 5
2.3 Reflex Decay....................................................................................................................... 7
2.4 Reflex Latency.................................................................................................................... 8
2.5 Eustachian Tube Function – Non-perforated Eardrum....................................................... 9
2.6 Eustachian Tube Function – Perforated Eardrum ............................................................ 11
2.7 Eustachian Tube Function – Patulous Eustachian Tube.................................................. 12
3The Setup Menu ............................................................................................................................ 13
3.1 Common settings – IMP.................................................................................................... 13
3.2 Protocol Settings............................................................................................................... 14
3.2.1 Tymp settings....................................................................................................... 15
3.2.2 Reflex settings...................................................................................................... 17
3.2.3 Reflex decay ........................................................................................................ 20
3.2.4 Reflex latency....................................................................................................... 22
3.3 Eustachian Tube Function – Non-Perforated Eardrum .................................................... 24
3.4 Eustachian Tube Function – Perforated Eardrum ............................................................ 26
3.5 Eustachian Tube Function – Patulous Eustachian Tube.................................................. 27
3.6 Pause................................................................................................................................ 28
3.7 Manage Protocol Settings................................................................................................. 29
3.8 Instrument Settings........................................................................................................... 30
4AT235 Audiometry Module............................................................................................................ 33
4.1 About the AT235 Audiometry Module............................................................................... 33
5General Operation of the AT235 Tympano-metry Module............................................................ 35
5.1 Tone Test.......................................................................................................................... 35
5.2 Auto Test: Hughson-Westlake.......................................................................................... 36
6The Setup Menu ............................................................................................................................ 37
6.1 Common Settings - AUD................................................................................................... 37
6.2Tone Settings.................................................................................................................... 38
6.3 Auto Settings..................................................................................................................... 39
7Quick Guides ................................................................................................................................. 41
7.1 Selecting the Correct Ear Tip............................................................................................ 41

AT235 Additional Information Page 1
1AT235 Tympanometry Module
1.1 About the AT235 Tympanometry Module
The AT235, including Tympanometry Module, is an electro-acoustic test instrument that produces controlled
levels of test tones and signals intended for diagnostic hearing evaluations and assessment of possible
otologic disorders. It features tympanometry and acoustic reflex functions. It also measures various acoustic
properties of the ear, including complex acoustic impedance and admittance, and equivalent ear canal
volume. These measures enable evaluation of the functional condition of the middle and outer ear.
The target population for the AT235, including Tympanometry Module includes all ages.
The AT235 including Tympanometry Module is designed to be used only by skilled personnel such as
audiologists, ENT surgeons, doctors, hearing healthcare professionals or personnel with a similar level of
training and expertise. The device should not be used without the necessary knowledge and training in its
use and in how to interpret results.
The Tympanometry Module contains the following tests:
•Tympanometry 226, 678, 800 and 1000Hz
•Ipsilateral reflexes
•Contralateral reflexes
•Reflex decay
•Reflex latency
•Eustachian tube function – non-perforated
•Eustachian tube function – perforated
•Eustachian tube function – patulous
Availability of these tests or specific settings within these tests on the hardware or in the software will vary
depending on the license purchased.
1.2 Preparing for the Test
1.2.1 Tympanometry patient instruction
Place the patient on a comfortable chair or, if necessary, on an examination table. Younger children may feel
more comfortable sitting on a parent's or nurse's lap. Show the probe to the patient and then explain the
following:
•The aim of the test is to assess the mobility of the eardrum
•The tip of the probe will be inserted into the ear canal and has to make a perfect seal
•A small amount of air will flow through the probe to move the eardrum; it produces a sensation
similar to pressing a finger slightly into the ear canal
•One or more tones will be heard during the test
•No active participation is expected from the patient
•Coughing, talking and swallowing will disturb test results
1.2.2 Visual inspection of the ear canal
Check the external ear canal for wax with an otoscope and remove any excessive wax to prevent the probe
opening from clogging, as this would inhibit testing. Excessive hairs may have to be cut.

AT235 Additional Information Page 2
1.2.1 Placement of the contralateral phones
If the contra headphone is used, place the headband over the patient's head. The audiometric headphone is
placed over the non-test ear (or contralateral reflex ear).
If the insert phone is used, mount the proper foam tip on the end of the tubing before inserting into the non-
test ear.
.

AT235 Additional Information Page 3
2General Operation of the AT235 Tympano-
metry Module
2.1 Tympanometry
The default display of tympanometry tests shows graphs for both left and right ear. The following information
is found in the display:
A
The label above the graphs indicates which probe tone frequency was used while measuring the
recording that is plotted.
B
The normative box which shows where the peak of the audiogram is expected in normal middle ear
functioning. The size of the normative box can be customized in the protocol setup. Be aware that
the placement of the normative box is dependent on the ear canal volume. This means that when
the curves are shown in non-compensated view, the box will only be placed correctly after the ear
canal volume is determined.
C
The tympanometry curve(s). The numerical values of the curve should be read from the left Y-axis.
For tympanometry performed at 226 Hz the scaling is in ml. For all other probe frequencies, the unit
at the Y-axis is mmho.
D
The equivalent ear canal volume. In automated tympanometry, the acoustic admittance (Y) at the
start pressure is taken as the reference value. In manually performed tympanometry, it takes the
acoustic admittance at the highest recorded pressure as a reference. Be aware that at probe
frequencies other than 226 Hz, the equivalent ear canal volume is read from right Y.
E
The table with measurement values. Here you will find:
•Volume, the equivalent ear canal volume
•Compliance, the peak compensated static acoustic admittance. When the tympanogram is
shown compensated for the ear canal volume, it is the compliance value at the peak.
•Pressure, the tympanic peak pressure which is at the point of the curve where the highest
compliance value is detected
•Gradient,If it is chosen to show gradient as pressure, it gives the tympanogram width at
half the height of the peak compensated static acoustic admittance. If it is chosen to show
gradient as compliance, it gives the average of the two compensated admittance values
which are 50 daPa away from the peak pressure.
If the automated measurement for some reason does not reach the end pressure as set in the
protocol setup, the table will only show the equivalent ear canal volume.

AT235 Additional Information Page 4
Manual Tympanometry Testing
F
The dot represents the measurement of the (non-compensated) acoustic admittance. It is only
shown when not recording. During recording the display will always be non-compensated.
G
The empty triangle indicates actual pressure.
H
The full triangle is the pressure cursor showing the current target pressure. It is moved by turning the
wheel.

AT235 Additional Information Page 5
2.2 Reflex
Note that in case your protocol has no reflex test included, you can temporarily include a reflex test in your
protocol by pressing the I Reflex C button.
The default displays of reflex tests show a matrix of reflexes, which are measured in the order of appearance
on the screen. The following information is found in the display:
A
The reflex matrix shows graphs of equal stimulus types in the rows and equal stimulus levels in the
columns. Note that scroll bars appear when more stimuli are available than can fit on the screen.
B
Within the graph, the x-axis is the time scale on which the black bar indicates when the stimulus
was given.
C
A green square indicates that the reflex threshold is set (either automatically or manually)at the
chosen stimulus level.
D
The Deflection value is shown when this option is activated through the protocol settings.
E
A grey square indicates a stimulus level that is not available for that particular stimulus type.
F
The square outlined in black indicates which section of the matrix has been selected or is currently
being measured.
Note that the reflexes are indicated by the probe ear. This is shown as an example below.
In the first setup, the probe is placed on the right ear and the contra headphone is placed on the left ear.

AT235 Additional Information Page 6
In the second setup, the probe is placed in the left ear with the contra headphone placed on the right ear.