natus Madsen Astera 2 User manual

Madsen® Astera²
User Guide
Doc. No.7-50-1350-EN/13
Part No.7-50-13500-EN

Copyright notice
© 2013,2021Natus MedicalDenmark ApS. All rights reserved. ® Natus, the NatusIcon, Aurical, Madsen, HI-PRO 2, Otoscan, ICS
and HORTMANN are registered trademarks of Natus MedicalDenmark ApS in the U.S.A. and/or other countries.
Version release date
2021-06-01 (221163)
Technical service and support
Please contact your supplier.
Madsen® Astera²
2

Table of Contents
1 Device description 4
2 Intended use 4
3 Unpacking 5
4 Installation 5
5 Powering the device 12
6 Connecting Madsen® Astera² to Otosuite 12
7 On-screen controls 13
8 PC keyboard controls 13
9 Toolbar icons in the Audiometry Module 13
10 The Sunshine Panel 15
11 Proper transducer placement 18
12 Performing tone audiometry 20
13 Performing speech audiometry 21
14 Maintenance 24
15 Other references 25
16 Technical specifications 26
17 Definition of symbols 41
18 Warnings, Cautions, and Notes 46
19 Manufacturer 51
Madsen® Astera² 3

1 Device description
Madsen® Astera² is a PC-controlled audiometer for testing a person's hearing.The audiometer is operated from the Oto-
suite Audiometry Module PC software.
With Madsen® Astera² you can perform standard audiometric tests, tone and speech audiometry and special tests.
• You can operate Madsen® Astera² from the PC’s keyboard/mouse, or from the Madsen® Astera² Audiometer Control
Panel (ACP) with the Otosuite Audiometry Software Module acting as the display.
• From the Otosuite Audiometry Software Module, which is NOAH compatible, you can monitor test results, create
User Tests, store and export data, and print reports.
Test intensities and frequencies as well as the current test settings and other information are shown on the PC mon-
itor.
2 Intended use
Madsen® Astera² and the Audiometry module
Users: audiologists, ENTs and other health care professionals in testing the hearing of their patients.
Use: diagnostic and clinical audiometric testing.
Intended Patient Population
The intended patient population is patients in all age groups, who are able to respond to the stimuli.
Clinical Benefit
Madsen® Astera²is used to conduct diagnostic and clinical audiometric testing, thereby providing a means to determine
the presence, type and degree of hearing loss, assist in the diagnosis of otologic disorders, and provide input for hearing aid
programming.
2.1 Typographical conventions
The use of Warning, Caution and Note
To draw your attention to information regarding safe and appropriate use of the device or software, the manual uses pre-
cautionary statements as follows:
Warning •Indicates that there is a risk of death or serious injury to the user or patient.
4 Madsen® Astera²
1 Device description

Caution •Indicates that there is a risk of injury to the user or patient or risk of damage to data or the device.
Note •Indicates that you should take special notice.
To obtain a free printed copy of the user documentation, contact Natus MedicalDenmark ApS (www.natus.com).
3 Unpacking
1. Unpack the device carefully.
When you unpack the device and accessories, keep the packing material in which they were delivered. If you need to
send the device in for service, the original packing material will protect against damage during transport.
2. Visually inspect the equipment for possible damage.
If damage has occurred, do not put the device into operation. Contact your local distributor for assistance.
3. Check with the packing list to make sure that you have received all necessary parts and accessories. If your package is
incomplete, contact your local distributor.
4. Check the Calibration Certificate to make sure that the transducers (headphones and bone conductor) are the correct
ones, and that they comply with the ordered calibration standards.
4 Installation
Install Otosuite on the PC before you connect Madsen® Astera² to the PC.
For Otosuite installation instructions, see the OtosuiteInstallation Guide, on the Otosuite installation medium.
To mount Madsen® Astera² on the wall or under the desktop, see the Madsen® Astera²Reference Manual.
Warning •To connect Madsen® Astera² to the PC, use the supplied USB cable. The cable length must not
exceed 3 m (approx. 10 feet).
Madsen® Astera² is fully assembled on delivery, and you simply have to connect the cables.
Madsen® Astera² 5
3 Unpacking

Remove the cable cover
1. To remove the cable cover from Madsen® Astera² press the releases
on both sides of the cable cover, swing the cover up into vertical
position and lift it off Madsen® Astera².
2. Lift off the cable cover.
Connect accessories
See Connecting accessories to Madsen® Astera² ►10.
Connect the ACP
If you are using the ACP:
See Connecting the ACP to Madsen® Astera² ►7and Connecting the ACP to the PC ►8.
Secure cables to Madsen® Astera²
1. Secure the cables to the back of Madsen® Astera² with the rubber
bands provided.
Remount the cable cover
1. Remount the cable cover by inserting the blue tags of the cable cover
into the grooves of Madsen® Astera² and swinging the cover into place
until you hear a click.
6 Madsen® Astera²
4 Installation

Connecting Madsen® Astera² to Otosuite
• Run the Otosuite Configuration Wizard to connect to and set up communication with Madsen® Astera²: Select Tools>
Configuration Wizard (Tools> Configuration Wizard)
4.1 Connecting the ACP to Madsen® Astera²
Note •Install Otosuite on the PC before you connect Madsen® Astera² to the PC.
1. Remove the cable cover from
Madsen® Astera².
2. Connect the ACP to the Mad-
sen® Astera² connection panel.
The connections are located at
the back of the ACP in the
"From Main Unit" group.
All four cables for connecting the ACP to Madsen® Astera² are joined in a bundle and color-coded for easy connection.
Warning •Make sure that each jack, as depicted on each end of the cable, connects with the specific sockets on
the ACP and Madsen® Astera².
Operator desktop microphone
• Connect the yellow cable in the cable bundle from the Operator desktop microphone
socket in the Madsen® Astera² rear panel to the Operator desktop microphone socket
in the ACP.
Operator monitor headset with boom microphone
• Connect the green cable in the cable bundle from the Operator monitor headset - head-
phones socket in the Madsen® Astera² rear panel to the Operator monitor headset -
headphones socket in the ACP.
• Connect the pink cable in the cable bundle from the Operator monitor headset - boom
microphone socket in the Madsen® Astera² rear panel to the Operator monitor headset
- boom microphone socket in the ACP.
Madsen® Astera² 7
4 Installation

Speaker, built into the ACP
• Connect the gray cable in the cable bundle from the Operator monitor speaker socket
in the MADSEN Astera² rear panel to the Operator monitor speaker socket in the ACP.
3. When you have connected the accessories, slide the cable cover onto Madsen® Astera² and click it into place.
4.2 Connecting the ACP to the PC
The ACP is powered from the PC through a USB connection.
Note •Install Otosuite on the PC before you connect the ACP to the PC.
Warning •To connect the ACP to the PC, use the supplied USB cable. The cable length must not exceed 3 m
(approx. 10 feet).
Note •Do not connect the ACP to the PC using a bus powered hub (USB hub without external power supply). It can-
not provide sufficient power to the ACP. The Power on LED on the ACP will flash to indicate an error. Use instead a
USB hub with external power supply.
The following applies only when used with the specified power supply, External power supply, Delta Elec-
tronics Inc., type MDS-090AAS24:
The installation must be carried out in accordance with :
• ANSI/AAMI ES60601-1 (2005/(R)2012 + A1:2012,C1:2009/(R)2012 + A2:2010/(R)2012) (Medical Elec-
trical Equipment - Part 1: General Requirements for Basic Safety and Essential Performance)
• CAN/CSA-C22.2 No. 60601-1:2014 (Medical electrical equipment – Part 1: General requirements for
basic safety and essential performance) - Edition 3 - Revision Date 2014/03
• ES60601-1:2005/(R)2012 and A1:2012
• Medical Electrical Systems clause 16 in IEC 60601-1 (3rd), AAMI ES60601-1 and CSA C22.2 NO. 60601-
1:2014
Warning •Any equipment connected with the device or used in the proximity of the patient must
comply with IEC60601-1-2 (4th Edition)and IEC 60601-1 (3rd).
8 Madsen® Astera²
4 Installation

The following applies only when used with the specified power supply, XP Power, type PCM80PS24:
The installation must be carried out in accordance with IEC 60601-1, UL 60601-1. The supplementary pro-
visions on the reliability of electro-medical systems.
Warning •Any equipment connected with the device or used in the proximity of the patient must
comply with IEC 60601-1 (Edition 2) and IEC 60601-1-2:2014.
Any PC connected to the ACP must comply with the requirements of UL/IEC 62368-1, "Safety of information
technology equipment, including electrical business equipment".
Only the supplied cable must be used for the connection.
Direct connection to PC using single USB cable
Warning •Make sure that the total length of the USB cable used for connecting the ACP to the PC does not
exceed 3 meters (10 feet).
1. Unfold the feet of the ACP.
2. Place the ACP in front of the PC monitor.
3. Plug one end of the USB cable into the USB socket located in the ACP rear panel and the other end of the
cable into a USB socket on the PC.
Connection to PC using externally powered USB hub
Caution •If the PC, the externally powered USB hub and the ACP are connected, make sure that you switch on
power to the hub before or right when you switch on the PC. This is to ensure that the USB connection between the
PC and the hub is established correctly. This connection is established when the PC is switched on.
Warning •If you are using an externally powered hub, no individual USB cable must exceed 3 meters (10 feet).
Power up sequence with externally powered USB hub
1. Connect the externally powered USB hub to the mains socket and switch it on.
2. Plug the single USB cable from the externally powered USB hub directly into a USB socket on the PC.
3. Connect the USB cable from the externally powered USB hub to the USB socket located in the ACP rear
panel.
Madsen® Astera² 9
4 Installation

4.3 Connecting accessories to Madsen® Astera²
Caution •Install Otosuite on the PC before you connect Madsen® Astera² to the PC.
The following applies only when used with the specified power supply, XP Power, type PCM80PS24:
The installation must be carried out in accordance with IEC 60601-1, UL 60601-1. The supplementary pro-
visions on the reliability of electro-medical systems.
Warning •Any equipment connected with the device or used in the proximity of the patient must
comply with IEC 60601-1 (Edition 2) and IEC 60601-1-2:2014.
except for the PC, and equipment connected to the line in and the line out sockets of Madsen® Astera².
The following applies only when used with the specified power supply, External power supply, Delta Elec-
tronics Inc., type MDS-090AAS24:
The installation must be carried out in accordance with :
• ANSI/AAMI ES60601-1 (2005/(R)2012 + A1:2012,C1:2009/(R)2012 + A2:2010/(R)2012) (Medical Elec-
trical Equipment - Part 1: General Requirements for Basic Safety and Essential Performance)
• CAN/CSA-C22.2 No. 60601-1:2014 (Medical electrical equipment – Part 1: General requirements for
basic safety and essential performance) - Edition 3 - Revision Date 2014/03
• ES60601-1:2005/(R)2012 and A1:2012
• Medical Electrical Systems clause 16 in IEC 60601-1 (3rd), AAMI ES60601-1 and CSA C22.2 NO. 60601-
1:2014
Warning •Any equipment connected with the device or used in the proximity of the patient must
comply with IEC60601-1-2 (4th Edition)and IEC 60601-1 (3rd).
• Except for the PC, and equipment connected to the line in and the line out sockets of Madsen® Astera².
See also Connector warnings ►46 and General warnings ►47.
For a detailed description of the connection panel, see the Madsen® Astera²Reference Manual.
Connection panel - Madsen® Astera²
The connections are located at the back of Madsen® Astera².
10 Madsen® Astera²
4 Installation

A. Patient Responders
B. Insert earphones
C. Headphones - air conduction
D. High-frequency headphones - air conduction
E. Bone conductor
F. Operator monitor headset - headphones
G. Operator monitor headset - boom microphone
H. Operator monitor speaker
I. Operator desktop microphone
J. Talkback microphone
K. Assistant monitor headset
L. Sound field speakers (power output)
M. External power supply
N. PC/USB connection
O. Line-in
P. Sound field speakers (line output)
Note •Blue corresponds to Left and red corresponds to Right.
Note •Use only the power supply provided by Natus.
Caution •When you connect other electrical equipment to Madsen® Astera², remember that equipment that does
not comply with the same safety standards as Madsen® Astera² can lead to a general reduction in the system's safety
level.
Connection panel - ACP
A. PC/USB connection • USB cable
B. Connections from Madsen® Astera² • Speaker built into the ACP
• Operator monitor headset with boom microphone
• Operator desktop microphone
C. Connections to accessories • Operator desktop microphone
• Operator monitor headset with boom microphone
Madsen® Astera² 11
4 Installation

5 Powering the device
Madsen® Astera² is powered through an external power supply connected directly to the mains outlet.
Switching on Madsen® Astera²
Use only the power supply provided by Natus.
1. Connect the mains plug of the external power supply directly to an AC mains outlet with a three-wire
protective ground.
2. Switch on the mains supply.
3. The On/Off indicator on Madsen® Astera² lights green.
Press the ON/OFF button on the front of Madsen® Astera².
Switching off Madsen® Astera²
1. To switch off Madsen® Astera², press the ON/OFFbutton on the front of Madsen® Astera².
Note •To switch off the mains supply, disconnect the power supply from the mains outlet.
6 Connecting Madsen® Astera² to Otosuite
When you use Madsen® Astera² for the first time, run the Configuration Wizard to set up the connection between Mad-
sen® Astera² and Otosuite. After you have configured Otosuite for the first time, if Madsen® Astera² is turned on when you
open the Control Panel in Otosuite, then Madsen® Astera² will connect to Otosuite automatically. Otherwise, you can con-
nect Madsen® Astera² as follows:
1. Switch on the device.
2. Launch Otosuite.
3. In the Otosuite toolbar, click Control Panel (Control Panel).
4. In the Control Panel, click Connect (Connect).
12 Madsen® Astera²
5 Powering the device

7 On-screen controls
Test controls provide a means of operating the audiometer if you use the mouse and on-screen options to perform tests.
• To enable test controls, select Tools> Options> Audiometry> General> On-screen controls> Show> On (Tools>
Options> Audiometry> General> On-screen controls> Show> On).
Silence Mode
Silence Mode allows you to control tone levels and presentation by hovering the mouse cursor over the respective on-
screen controls. This is particularly useful when the operator of the audiometer and the person being tested are in the
same room.
• To enable silence mode, select Tools> Options> Audiometry> General> On-screen controls> Silence Mode> On
(Tools> Options> Audiometry> General> On-screen controls> Silence Mode> On).
• To change the level and frequency by more than one click at a time, use the mouse scroll wheel.
8 PC keyboard controls
You can open a separate PDF-file to have a proper view of the keyboard short-
cuts.
After you install Otosuite, you can find Otosuite manuals and related doc-
umentation on your PC. In the Start (Start) menu, open OtosuiteManuals,
which contains an overview with links to all manuals.
Note •The actual position of the keys may depend on your keyboard
type.
9 Toolbar icons in the Audiometry Module
The icons available in the toolbar depend on the test function that you have selected.
Madsen® Astera² 13
7 On-screen controls

Audiometry icons
Tone audiometry
Speech audiometry
Menu item Icon Description
Combined Audiogram
(Combined Audiogram)
Click to toggle between viewing both ears in a single audiogram (com-
bined audiogram) or both a left and a right audiogram on your screen.
Combined View (Combined View)
• Click to view both ears in a single audiogram.
Split View (Split View)
• Click to view separate audiograms for each ear.
Masking Assistant
(Masking Assistant)
Enable or disable the Masking Assistant.
The Masking Assistant causes an unmasked threshold to flash
repeatedly if masking is recommended.
Standard Frequencies
(Standard
Frequencies)/All Fre-
quencies (All Fre-
quencies)/ High
Frequencies (High Fre-
quencies)
The graph shows up to 20000 Hz. Madsen® Astera² presents stimulus
up to 12500 Hz.
• Click to choose between viewing:
Standard Frequencies (Standard Frequencies)
Displays the audiogram from 125 Hz to 8000 Hz.
All Frequencies (All Frequencies)
Displays the audiogram from 125 Hz to 20000 Hz.
High Frequencies (High Frequencies)
Displays the audiogram from 8000 Hz to 20000 Hz.
New Audiogram (New
Audiogram)
Select new audiogram. You will be prompted to save or cancel current
data.
14 Madsen® Astera²
9 Toolbar icons in the Audiometry Module

Menu item Icon Description
Frequency Resolution
(Frequency Resolution)
The options for frequency resolutions are 1/6, 1/12, 1/24 and 1/48
octave as well as 1 Hz. Select the different tone stimulus resolutions
from the toolbar or from Tools> Options> Audiometry> General
(Tools> Options> Audiometry> General).
You can store up to 24 points for each audiometry curve. You will be
prompted if you try to store more than the maximum number of
points.
Monitoring (Mon-
itoring)
Enables or disables the monitor speaker for monitoring stimuli presen-
ted to the patient from the Stimulus (Stimulus) or Masking (Masking)
channel.
Desktop/Headset
Microphone
(Desktop/Headset
Microphone)
Toggle microphone types (Toggle microphone types)
Click to toggle between the operator headset boom microphones and
desktop microphone used to communicate with the patient and/or the
assistant. The one displayed is the one currently active.
Enable Talk to Assist-
ant (Enable Talk to
Assistant)
Click to enable or disable talking to another party (usually a second
tester) in the booth.
Talk Forward (Talk For-
ward)
Enables communicating with the patient in the sound booth. This will
display the Talk Forward (Talk Forward) dialog box, where you can con-
trol the talk forward microphone sensitivity and the output level in dB
HL to the patient.
Select Orientation
(Select Orientation)
Click to select the perspective of the patient's ears as presented on the
screen for graph and table views.
You can also select the location of the stimulus control.
Sunshine Panel (Sun-
shine Panel)
When you have enabled the Control Panel icon on the toolbar, you can
choose between using the Classic Control Panel and the Sunshine
Panel.
Live Video Otoscopy Click to launch a Live Video Otoscopy.
10 The Sunshine Panel
Click the Control Panel (Control Panel) icon in the toolbar to activate the Control Panel.
Click the Sunshine Panel (Sunshine Panel) icon in the toolbar to select or deselect the Sunshine Panel in
either Tone (Tone) or Speech (Speech) testing.
Madsen® Astera² 15
10 The Sunshine Panel

Tone testing Speech testing
Use the Sunshine Panel to quickly select the main settings for testing.
In the Sunshine Panel you can quickly select test ear, transducer, masking,
and test type.
You can control the monitor level, activate the Talk Forward (Talk For-
ward) dialog, and select the Test Selector (Test Selector) for quickly
selecting the relevant user test.
Your selections are shown in the Stimulus (Stimulus) bar and as symbols
in the audiogram.
See also
•Performing tone audiometry ►20
•Performing speech audiometry ►21.
Customizing the Sunshine Panel
You can customize the Sunshine Panel to display one or several buttons for some of the functions. For instance you can dis-
play one or more of the curve selection buttons on the panel.
When the right-click menu for a button includes the selection Add/Remove buttons (Add/Remove buttons) you can cus-
tomize the setup.
1. Enable/disable the button(s) you wish to display.
2. Click to disable the selection Use Single Button (Use Single Button). The enabled buttons are displayed immediately
in the panel.
Using the Sunshine panel
• Click on the buttons to toggle the selection
or
• Right-click on a button to select a combination of functions.
16 Madsen® Astera²
10 The Sunshine Panel

Function Icon Description
Stimulus Ear Selection
(Stimulus Ear Selec-
tion)
Click to select test ear:
•Right (Right)
•Binaural (Binaural)
•Left (Left)
Transducer Selection
(Transducer Selection)
Click to select the transducer used for the test ear:
•Insert (Insert) (earphones)
•Phone (Phone) (standard headphones)
•High Frequency (High Frequency) (headphones)
•Bone (Bone) (conductor)
•SF Unaided (SF Unaided) (Sound Field speaker, unaided)
•SF Aided 1 (SF Aided 1) and SF Aided 2 (SF Aided 2) (Sound field speaker -
Aided 1 and 2
•Multispeaker (Multispeaker)
Masking Transducer
Selection (Masking
Transducer Selection)
Click to select the transducer used for the masked ear:
•Insert (Insert) (earphones)
•Phone (Phone) (standard headphones)
•High Frequency (High Frequency) (headphones)
•Bone (Bone) (conductor)
•SF (SF) (Sound Field speaker)
•SF Aided 1 (SF Aided 1) and SF Aided 2 (SF Aided 2) (Sound field speaker -
Aided 1 and 2)
Masking Options
(Masking Options)
Mask
(Mask)
Click to enable or disable masking.
Stimulus Selection
(Stimulus Selection)
Click to select stimulus type.
• Tone (Tone testing)
• Warble (Tone testing)
• FRESH noise (Tone testing)
• Pre-recorded stimulus (Speech)
• Microphone to present live speech stimulus (Speech)
Madsen® Astera² 17
10 The Sunshine Panel

Function Icon Description
Curve Selection (Curve
Selection)
Click to select the curve type:
•THR (THR) (Threshold level) (Tone)
•MCL (MCL) (Most Comfortable Loudness level)
•UCL (UCL) (Uncomfortable Loudness level)
•SDT (SDT) (Speech Detection Threshold) (Speech)
•SRT (SRT) (Speech Recognition Threshold) (Speech)
•WRS/SRS (WRS/SRS) (Word Recognition Score/Sentence Recognition
Score) (Speech)
Talk Forward (Talk For-
ward)
The Talk Forward (Talk Forward) dialog is described in the Madsen® Aster-
a²Reference Manual.
Monitor/Level (Mon-
itor/Level)
•Monitor (Monitor)
Click to enable monitoring of the stimulus channel.
•Level (Level)
Adjust the slider to set the preferred monitoring level for the respective
audiometer channels.
Test Selector (Test
Selector)
The Test Selector (Test Selector) dialog is described in the OtosuiteUser
Guide.
11 Proper transducer placement
Headphones
1. Loosen the headband and place both the left and right side of the headphones simultaneously.
Note •If the headphones are not placed properly, there is risk of causing the ear canal to collapse which will result in
elevated thresholds.
2. Aim the center of the headphones towards the patient's ear canals and gently place them against the ears.
3. Tighten the headband while holding the headphones in place with your thumbs.
4. Examine the placement of the headphones to make sure they are level, and properly positioned.
Insert Earphones
1. Select the largest foam eartip that will fit into the patient's ear.
If the eartip is too small the sound will leak out and the sound level will not be accurate at the eardrum.
Insert earphones have greater attenuation between ears especially at the low frequencies; this reduces the need for
masking.
18 Madsen® Astera²
11 Proper transducer placement

2. It is best to clip the insert earphone transducers behind the child or on the back of their clothing and then fit the
foam eartip into the child's ears.
Bone Conductor
Note •For unmasked bone thresholds, you can store binaural data:
If there is a difference of 10dB or greater between the bone conduction threshold and the air conduction threshold of
the same ear, masking is needed. The Masking Assistant can assist you in determining which thresholds need to be
masked.
If the SRT of the test ear and the bone conduction PTA of the nontest ear differ by 45 dB or more, masking is needed.
Mastoid placement
1. Move any hair covering the mastoid out of the way and place the flat round part of the bone conductor securely on
the boniest portion of the mastoid without any part of the transducer touching the external ear.
2. Make sure the bone conductor is tight on the mastoid but still comfortable.
3. If you are going to perform masking with earphones, position the other end of the bone conductor headband over the
patient's temple on the opposite side of the head so that the headband of the earphones and bone conductor fit on
the patient's head.
Forehead placement
1. For frontal bone placement, place the flat round part of the bone conductor securely on the middle of the forehead
about an inch (2.5 cm) below the hairline.
2. Make sure the bone conductor is tight on the forehead but still comfortable.
Madsen® Astera² 19
11 Proper transducer placement

12 Performing tone audiometry
Sunshine Panel
A. Ear selection
B. Stimulus transducer
C. Masking, transducer and On/Off
D. Stimulus type
E. Test type
F. Talk Forward dialog
G. Monitor/Level
H. Test Selector
Classic Control Panel
A. Control Panel
B. Test Options panel
C. Monitor/Level panel
Whenever the test buttons and other functions are used, you can use the corresponding keys on the keyboard, or the on-
screen controls located at the top of the screen or in the Control Panel to the left.
For detailed examples of audiometric testing, see the Madsen® Astera² Reference Manual.
1. Select the Tone (Tone) screen in the Otosuite Audiometry module.
2. Prepare the patient. If you wish to instruct the patient after you have placed the transducers on the head of the
patient, you can use the Talk Forward (Talk Forward) button. You can talk to the patient to adjust the patient com-
munication levels when Talk Forward (Talk Forward) is active.
3. In the Control Panel, select test conditions for ear, transducer, unmasked/masked, and test type.
4. Select the test frequency with the Right/Left arrow buttons (or on keypad).
5. Select the stimulus level with the Up/Down arrow buttons (or on keypad).
6. Present the tone stimulus with the Present (Present) button or the space bar on the keypad.
20 Madsen® Astera²
12 Performing tone audiometry