Audera User Manual AEP CAEP

Part Number 2001-0141 Rev. B

Blank page.

Title:

GSI Audera AEP/CAEP User Manual

Copyright © 2011 Grason-Stadler, Inc. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means without the prior written permission of Grason-Stadler Inc. The information in this publication is proprietary to Grason-Stadler, Inc.

Compliance The CE0344 mark identifies compliance with the Medical Device Directive 93/42/EEC. Grason-Stadler, Inc. is an ISO 13485 certified corporation.

European Authority Representative Grason-Stadler Kongebakken 9 2765 Smørum Denmark

0344

2001-0141 Rev. B

i

GSI Audera

Additional copies Additional copies of this manual or other GSI literature may be obtained from:

Attention The information in this document is subject to change without notice. Grason-Stadler makes no warranty of any kind with regard to this material, including, but not limited to the implied warranties of merchantability and fitness for a particular purpose. Grason-Stadler assumes no responsibility for any errors that may appear in this document. GrasonStadler makes no commitment to update or to keep current the information contained in this document.

Trademarks Microsoft, MS, Windows, Window XP, Windows NT and Windows 7 are registered trademarks of Microsoft Corporation. Pentium is a trademark of Intel Corporation. Audera is a trademark of Grason-Stadler, Inc.

ii

2001-0141 Rev. B

System warranty Grason- Stadler warrants that each product we sell shall conform to its product specifications as defined in the user documentation. If the product does not function as warranted during the warranty period, we will repair or replace it without charge. If in our judgment we are unable to do so, it may be returned for a refund. Warranty period

The warranty period is stated in the product user documentation. The warranty period for products sold outside the U.S.A. and Canada is 12 months from the date of installation or 14 months from the date of shipment, whichever is less.

Limit of warranty

Misuse, accident, modification, unsuitable physical or operating environment, improper maintenance, or damage caused by a product for which we are not responsible may void the warranty. Certain components may have separate warranty periods as stated in the product user documentation. Consumables are not covered under warranty. THIS WARRANTY REPLACES ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE AND ANY OTHER OBLIGATIONS OR LIABILITIES ON THE PART OF GRASON-STADLER INC. WHETHER IN CONTRACT, WARRANTY, NEGLIGENCE OR OTHERWISE. GRASON-STADLER SHALL NOT BE LIABLE FOR AND DISCLAIMS ALL CONSEQUENTIAL, INCIDENTAL AND CONTINGENT DAMAGES.

Items not covered by warranty

Grason-Stadler, Inc. does not warrant uninterrupted or error-free operation of a product. Grason-Stadler, Inc. provides certain non-GSI products on an “as is” basis. Non-GSI manufacturers or suppliers may provide their own warranties. Separate software warranty is provided with software user documentation.

2001-0141 Rev. B

iii

GSI Audera

Software warranty Grason-Stadler Inc. warrants that the physical media (e.g. CDs), shall be free of malfunction in labor and materials for a period of ninety (90) days from the invoice date. If the physical media containing the software is defective, GSI will replace it without charge. In no event will GSI liability exceed the price paid for the software, regardless of the form of the claim. GSI does not warrant that the software will operate uninterrupted or error-free. GRASON-STADLER MAKES NO OTHER WARRANTIES, EITHER EXPRESSED OR IMPLIED, WITH RESPECT TO THIS SOFTWARE, INCLUDING WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. GSI MAKES NO WARRANTY, EITHER EXPRESSED OR IMPLIED, WITH RESPECT TO THE QUALITY OR PERFORMANCE OF THIS SOFTWARE. GSI SHALL NOT BE LIABLE FOR CONSEQUENTIAL, INCIDENTAL OR CONTINGENT DAMAGES. Some states do not allow the exclusion or limitation of implied warranties or limitation of liability for incidental or consequential damages, so the above limitation or exclusion may not apply. Software copyright protection

This software is protected by state, U.S. and international copyright treaty provisions. These copyright provisions apply to the use of this software regardless of whether or not the following terms are agreed upon. Under law, copyright infringers may be liable for actual damages sustained by the copyright owner and for punitive damages of up to $100,000 per infringement. Unauthorized copying of computer software, and attempts to do so, are also criminal violations, with penalties that may exceed $100,000 in fines and 10 years in prison. 1.

Unless restricted by an agreement with GSI, the following is permitted: a. Use this software on only one computer and by one user at a time. b.

Make one copy of this software, provided that, (i) the copy is created as an essential step in the utilization of this software in conjunction with the machine and that it is used in no other manner, or (ii) the copy is for archival purposes only and that all archival copies are destroyed in the event that the continued possession of this software should cease to be rightful.

c. Sell this software, and any archival copy, only as part of the sale of all of the rights in this software, except that adaptations so prepared may be transferred only with the authorization of GSI. 2.

The following is not permitted: a. Make copies of this software or documentation except as described above. b. Alter, modify or adapt this software or documentation except as described above. c. Distribute, lease, rent or sublicense this software or documentation.

iv

2001-0141 Rev. B

Customer responsibility This product and its components will perform reliably only when operated and maintained in accordance with the instructions contained in this manual, accompanying labels, and/or inserts. A defective product should not be used. Parts which may be broken or missing or are plainly worn, distorted or contaminated should be replaced immediately with clean, genuine replacement parts manufactured by or available from GSI. The responsibility of GSI for a malfunctioning product is limited by the warranty set forth in this manual. Should repair or replacement of this product become necessary after the warranty period, the customer should seek advice from GSI Technical Support prior to such repair or replacement. If this product is in need of repair, it should not be used until all repairs have been made and the unit is functioning properly and ready for use. The owner of this product has sole responsibility for any malfunction resulting from improper use or maintenance, or repair by anyone other than GSI, and from any malfunction caused by parts that are damaged or modified by anyone other than GSI.

Regulatory standards GSI Audera systems meet the following safety standards set by domestic and international regulatory agencies for Medical Electrical Equipment.    

UL 60601-1 – American Standards for Medical Electric Equipment General Requirements CAN/CSAC 22.2 No. 601.1-M90 Canadian General Requirements for Medical Electrical Equipment IEC/EN 60601-1 International Standards for Medical Electrical Equipment General Requirements IEC/EN 60601-2-40 Particular Requirements for the Safety of Electromyographs and Evoked Response Equipment

CAUTION Federal law in the USA and Canada restricts the sale, distribution or use of this product to, by, or on the order of a licensed medical practitioner.

2001-0141 Rev. B

v

GSI Audera

About GSI Audera The GSI Audera system provides all the functionality needed to perform the following auditory evaluations:

• • • •

Auditory Evoked Potentials Cortical Auditory Evoked Potentials Electrocochleography Auditory Middle Latency response

Protective classification

This system is intended for continuous operation and has a protective classification of Class I, Type BF and Type B applied parts, ordinary equipment, not suitable for use in the presence of flammable anesthetics.

Intended operator

The system is intended as an aid for users trained and skilled in audiology.

User interface

• • •

A pointing device (mouse, touchpad, or track-ball) Standard Windows™ toolbars with customized icons and sliders Keyboard short cuts

Output interface

•

Windows-supported printers

Identifying the GSI Audera software version number To locate which version of software is loaded on this system; 1.

Open the GSI Audera application.

2.

From the Menu Bar, click on Help.

3.

Click on About GSI Audera. The software version number is displayed on the About GSI Audera panel.

Requirements The GSI Audera package requires a GSI Audera hardware platform in order to operate. Input requirements

System Power: 115W, excluding printer Frequency Range: 50-60 Hz AC Voltage/Current: 100V-120V/11.5A-9.6A/250V 220V-240V/5.3A-4.8A/250V Fuse: 5x20mm 100V-120V: T10AL 220V-240V: T5AL

vi

2001-0141 Rev. B

Safety Summary This section describes the types of safety symbols used in this guide and lists the Warnings and Cautions found in this manual.

WARNING The WARNING label identifies conditions or practices that may present danger to the patient and/or user.

CAUTION

The CAUTION label identifies conditions or practices that could damage

the equipment or lose data.

NOTE!

The NOTE label helps identify areas of possible confusion and avoid potential problems during system operations.

______________________________________________________________ IMPORTANT! Please read and follow all WARNING, CAUTIONS, and NOTES provided in this guide. To avoid the possibility of injury, damage to the system or lost data, observe these safely precautions during system operations.

2001-0141 Rev. B

vii

GSI Audera

Safety precautions The following safety precautions must be observed at all times:

!

WARNING

FAILURE TO OBSERVE THESE REQUIREMENTS COULD RESULT IN SERIOUS INJURY OR DEATH. This device should only be used by hearing health care professionals such as an audiologist, otolaryngologist, researcher or a technician under the direct supervision of the fore mentioned specialists. Users should apply their professional skills when interpreting the results and this should be done in conjunction with other testing as deemed appropriate. This device is rated “Type BF.” This means the device is not insulated sufficiently to be considered totally isolated electrically and dangerous leakage currents can occur. In particular, a. b. c.

The earphone connector at the transducer box has an air gap small enough to allow the possibility of a mains powered cable in close contact, or in direct contact, to leak current into the unit and the earphones via the earphone cable. The GSI Audera amplifier could leak current to the electrodes connected to the patient if a mains powered cable comes in close contact, or in direct contact, with the metallic parts on the GSI Audera amplifier (such as the electrode test inputs). The OAE probe could leak current to the eartip connected to the patient if a mains power cable comes in close contact, or in direct contact, with OAE probe parts.

Users should take the necessary precautions for environments or situations that require “Type BF or Type CF” protection. Contact the hospital’s Bio-medical engineering department or call GSI for clarification as required. The GSI Audera amplifier must be used only with electrodes and leads designed to suit its connectors. These leads are designed to avoid accidental conduction of dangerous voltages to the patient. Ensure that the earth connection at the mains electrical power outlet is properly grounded. Standard clinical precautions must be taken when testing sedated or anesthetized patients. Do NOT use in the presence of flammable gaseous mixtures. Users should consider the possibility of explosions or fire when using this device in close proximity to flammable anesthetic gases. Discuss with the anesthetist. Installation of third party software packages can affect the functionality of the software and may cause malfunctions. Do not use extension cords for the Isolation Box. Extension cords can cause ground integrity and impedance problems. When used simultaneously with high frequency surgical equipment, burns may occur at the site of any recording or stimulating electrode.

viii

2001-0141 Rev. B

this

Advise patients with implanted electronic devices not to be subjected to electrical stimulation unless specialist medical opinions have first been obtained. Electrodes of inadequate size or unsuitable application could provoke skin reactions or burns. These electrodes contain an adhesive that maintains the electrode skin position and contact during electrical stimulation. The maximum sound levels that can be generated by the system can cause serious injury to the ear. Before attaching the earphones to the patient, ensure that, a. the system is running. b. the hearing levels in the test set to be used are appropriate. c. a biological check of the system has been performed. In addition to electrical safety considerations, poorly earthed mains power outlets are likely to cause inaccurate test results due to the introduction of electrical interference from the mains. As a safety precaution, at time of delivery the system’s output default limit is set to 90 dB SPL. To present stimuli at higher levels, the default setting may be increased to a maximum of 130 dB SPL. Click on Options > Main Options > Artificial Audio Level Limit.

This Warning symbol indicates a stimulus level of 95 dB SPL or greater can now be delivered. At high stimulus levels (>100 dB peSPL) the electrode leads should be placed away from the earphone transducer boxes and cables, or artifacts may result. The earphones supplied use plastic tubes to reduce the possibility of electrical interference with the electrode leads. Separate the Insert earphones and the electrode leads, in order to minimize the possibility of electrical coupling. Bone vibrators are especially vulnerable to producing artifacts. Only a level of 55 dB is required with a bone vibrator to produce an artifact that would require a level of 100 dB using earphones. This is compounded by placing the bone vibrator close to the electrode on the mastoid. The following common deficiencies will adversely affect testing: 1.

Using blocked earphones

2.

Using earphones designated and calibrated for one channel with the other channel, when that channel is using another earphone calibration file 3. Using incorrect calibration files for the earphones in use 4.

Using an OAE probe without its corresponding calibration file loaded

For optimal ASSR results, the patient should be asleep.

2001-0141 Rev. B

ix

GSI Audera

The GSI Audera System unit is designed for 50 Ohm earphones only. Some Insert earphones are 10 or 300 Ohms, and are not suitable for use with our system. This warning also applies to bone conduction oscillators and other types of headphones. The speaker is 8 ohms. The tubes on the TIP-50 insert earphones should never be changed in length, as this affects the acoustics of the earphones.

CAUTION The Audera system is designed to operate in an air-conditioned environment. The maximum temperature at which the system should be used is 30 degrees Celsius. The unit should be placed in a position that allows adequate ventilation. Avoid placing it in the proximity of other equipment that may also produce heat. Operation at temperatures above 30 degrees Celsius could damage the GSI Audera System. Do not stack any item of equipment on top of the GSI Audera System Unit (other than a laptop computer when appropriate). The modulation frequencies need to be selected carefully when making custom ASSR test sets. Avoid modulation frequencies that have a fundamental or harmonic relationship to the frequency used in the country’s mains power supply (50 or 60 Hz), and its harmonics. Using these frequencies can give erroneous results as the power supply’s voltage could be imposed on them. Other frequencies such as the refresh frequencies used by computer monitors (typically 60 to 100 Hz) can also cause erroneous results. Refer to the manual supplied with the computer monitor if in doubt. Proper use of this software depends on careful reading of all instructions and labels. Federal law in the U.S.A. and Canada restricts the sale, distribution or use of this device to, by or on the order of a licensed medical practitioner. Do not attempt to reinstall the software without consulting a qualified GSI Service Representative first. All data may be lost. Follow the steps provided only under the direction of a qualified Service Representative. Follow the Shutdown sequence described in the system's User manual to turn off the system to ensure the integrity of the data files. Use this device in humidity controlled medical use rooms with an anticipated humidity range of 20 to 80%. All nonmedical equipment connected to this device, such as printers, must comply with IEC 950 and/or appropriate European Directives. Connect all nonmedical equipment to the GSI Isolated Power Supply. Turn OFF system power before cleaning. Prevent detergent solution or cold sterilization agents from seeping into the electronics of the instrument. Be especially careful around controls, connectors and panel edges. Do not use abrasives.

x

2001-0141 Rev. B

If the system is not functioning properly, do not operate it until all necessary repairs are made and the unit is tested for proper functioning in accordance with GSI published specifications. It is recommended that all repairs be performed by a qualified service representative only. Do not disconnect or reconnect the amplifier cable with system power on. This may damage the amplifier. Inspect the power cord often for fraying or other damage. Do not operate the apparatus with a damaged power cord or plug. The AC power outlets on the iso-power box are intended for use with GSI approved components only. Use of any other equipment may result in damage to the power unit. Follow all safety standards set by each facility. Do not over tighten the connector securing screws. The customer is responsible for maintaining all system software in a safe, secure location. IMPORTANT! Do not attempt any procedures requiring specialized test equipment or access to the interior of this instrument. Switch off all power to the system before attempting any service and maintenance. Approved Electrodes: Use only GSI approved/supplied electrodes and transducers. See a GSI Distributor. Use of non-approved electrodes or transducers might adversely affect the function of the system. The USB cable and connectors are delicate. Be careful not to kink or sharply bend the cable. It should not be coiled to a diameter less than 15 cm. Do not use excessive force or use force delivered at an angle when unplugging the amplifier or probe connectors. Damage to the amplifier cable, probe, or connectors is not covered by warranty. The repetition rate needs to be selected carefully when making custom Test Sets:

2001-0141 Rev. B

•

Avoid repetition rates that have a fundamental or harmonic relationship to the frequency used in the country’s main power supply (50 or 60 Hz) and it harmonics. Using these rates can give erroneous results as the power supply’s voltage could impose on them.

•

Other rates such as the refresh rates used by computer monitors (typically 60-100 Hz) can also cause erroneous results. Refer to the manual supplied with the computer if in doubt.

xi

GSI Audera

Blank page.

xii

2001-0141 Rev. B

Table of Contents

Additional copies .............................................................................................................................. i-ii Attention............................................................................................................................................ i-ii Trademarks ....................................................................................................................................... i-ii System warranty.............................................................................................................................. i-iii Warranty period ............................................................................................................................ i-iii Limit of warranty.......................................................................................................................... i-iii Items not covered by warranty ......................................................................................................i-iii Software warranty........................................................................................................................... i-iv Software copyright protection ...................................................................................................... i-iv Customer responsibility ....................................................................................................................i-v Regulatory standards ........................................................................................................................i-v About GSI Audera........................................................................................................................... i-vi Protective classification................................................................................................................ i-vi Intended operator.......................................................................................................................... i-vi User interface ............................................................................................................................... i-vi Output interface............................................................................................................................ i-vi Identifying the GSI Audera software version number ................................................................ i-vi Requirements .....................................................................................................................................i-vi Input requirements........................................................................................................................ i-vi Safety summary .............................................................................................................................. i-vii Safety precautions ......................................................................................................................... i-viii

AEP/CAEP Introduction Overview.......................................................................................................................................... 1-3 Electromagnetic Compatibility Guide.......................................................................................... 1-3 GSI Audera AEP/CAEP Application Software ........................................................................... 1-3 Customizable Software .................................................................................................................. 1-3 Terminology .................................................................................................................................... 1-4 Summary of mouse operations available...................................................................................... 1-4 How it works ................................................................................................................................... 1-5 Auditory Evoked Response ......................................................................................................... 1-5 Calibration Procedures………………………………………………………………………….. 1-6 Impact of New Calibration on Testing…………………….….….….……..…........................... 1-6 Electrocochleography.................................................................................................................. 1-7 Electrical Auditory Evoked Potentials ........................................................................................ 1-8 Repeatability check ..................................................................................................................... 1-8

2001-0141 Rev. B

i

GSI Audera AEP/CAEP Screens Introduction...................................................................................................................................... 2-3 AEP/CAEP Acquisition screen....................................................................................................... 2-4 The single screen is divided into 8 sections ................................................................................. 2-4 The split screen is divided into 8 sections .................................................................................... 2-5 1. Menu bar................................................................................................................................... 2-5 2. Cursor Display Boxes ............................................................................................................... 2-5 3. Previous Results display........................................................................................................... 2-6 4. Current Acquisition display...................................................................................................... 2-7 5. Ongoing EEG display............................................................................................................... 2-7 6. Acquisition Screen Control Panel............................................................................................. 2-7 7. Test Status display .................................................................................................................. 2-10 8. Communication Status............................................................................................................ 2-10 AEP/CAEP Review screen ............................................................................................................ 2-11 1. Menu Bar ................................................................................................................................ 2-12 2. Toolbar buttons ....................................................................................................................... 2-16 3. Left and Right Charting Panels .............................................................................................. 2-18 4. Hierarchical Tree .................................................................................................................... 2-19 5. Review Screen control panel .................................................................................................. 2-20 6. Cursor Display/Measurement Display.................................................................................... 2-21

Performing AEP/CAEP Tests Prepare the system........................................................................................................................... 3-3 Prepare the patient .......................................................................................................................... 3-3 Check the impedance....................................................................................................................... 3-4 Impedance Test window ............................................................................................................... 3-4 Quick start AEP testing .................................................................................................................. 3-5 Performing an AEP test ................................................................................................................ 3-5 Automatic testing ............................................................................................................................. 3-7 Using Auto Test ............................................................................................................................ 3-7 Controlling the Auto Test ............................................................................................................. 3-7 Creating Custom AEP Test Sets ..................................................................................................... 3-8 1. Test Set...................................................................................................................................... 3-8 2. Test Item ................................................................................................................................. 3-11 3. Function keys.......................................................................................................................... 3-13 Filters .............................................................................................................................................. 3-15 Digital versus analog .................................................................................................................. 3-15 Linear phase versus nonlinear phase .......................................................................................... 3-15 Low pass filters........................................................................................................................... 3-15 High pass filters .......................................................................................................................... 3-15

ii

2001-0141 Rev. B

Table of Contents

Analyzing AEP/CAEP Tests Reviewing and analyzing acquired data.........................................................................................4-3 Markers .............................................................................................................................................4-4 Placing markers on a waveform ....................................................................................................4-4 Moving markers ............................................................................................................................4-4 Deleting markers ...........................................................................................................................4-4 Text markers ..................................................................................................................................4-5 To Edit a Marker Set......................................................................................................................4-9 Printing an AEP Report.................................................................................................................4-12 Printing an AEP Chart .................................................................................................................4-12

Appendix Auditory Brainstem Response (ABR).............................................................................................5-2 The Test Setup ...............................................................................................................................5-2 The Response ................................................................................................................................5-3 Electrical Auditory Brainstem Response (EABR).........................................................................5-4 The Test Setup ...............................................................................................................................5-4 The Response ................................................................................................................................5-5 Electrocochleography (ECochG) ....................................................................................................5-6 The Test Setup ...............................................................................................................................5-6 The Response ................................................................................................................................5-7 Earphone Delay Justification.........................................................................................................5-7

2001-0141 Rev. B

iii

GSI Audera Blank page.

iv

2001-0141 Rev. B

1

2001-0141 Rev. B

AEP/CAEP Introduction

1-1

GSI Audera

Blank page.

1-2

2001-0141 Rev. B

AEP/CAEP Introduction

Overview Grason-Stadler, Inc. proudly continues the tradition of equipment excellence with Grason-Stadler instruments, a world leader in screening and diagnostic audiological equipment for over 50 years. The GSI Audera AEP/CAEP provides test capabilities for Auditory Brainstem Response, Electrocochleography, Auditory Middle Latency Responses, Cortical Auditory Evoked Potentials, and Electrical Auditory Evoked Potentials in a computer based system available in two versions: a portable and a desktop system. The GSI Audera AEP/CAEP system consists of a USB interface between the GSI Audera base unit, a digital 2-channel amplifier, transducers (inserts, bone vibrator, or speaker), and a software application installed on a computer.

Note: The GSI Audera isolation transformer must be used when a laser printer or external monitor is attached to the portable version of the system, or when using a desktop system.

Electromagnetic Compatibility Guide Please refer to the Electromagnetic Compatibility Guide on CD (part number 269-5962xx) or page vii of this User Manual for information concerning the GSI Audera system.

GSI Audera AEP/CAEP Application Software The GSI Audera AEP/CAEP Application software operates with the Microsoft Windows environment on the XP Pro, Vista Business or Windows 7operating system. It uses a Microsoft SQL Database to store patient information on the hard drive and allows the retrieval of patient data by name, session, test type, etc.

Customizable Software The flexible nature of the software allows the development of libraries of test protocols that are appropriate for the populations being tested. Simply selecting the protocol name (custom) sets up the equipment for testing that population. Default Test Sets for screening and diagnostic protocols are also provided.

2001-0141 Rev. B

1-3

GSI Audera

Terminology It is important to note the terminology that will be used in the following description of the Review screen and their relationship to each other. Other than Function keys, the Review screen is mainly comprised of Panels, Charts and Waveforms. A Panel is an area of the screen that contains charts; there are two panels. A Chart is a window within a panel that contains waveforms; there may be many charts. A Waveform is the result of a test/trial or a mathematical operation such as average, add or subtract. There may be many waveforms. The Panels, Charts and Waveforms represent a “hierarchy” from highest to lowest and are shown on the Hierarchical Tree. Snapped means the chart cursor has been “captured” by a point on a waveform. When the cursor is moved within the capture range of a waveform, the cursor jumps to and locks onto that waveform. When this occurs, the chart cursor is displayed as a “hand” at the cursor intersection.

Summary of mouse operations available Single left click on a chart when not snapped to a waveform.

•

Selects the chart and the chart is highlighted on the Hierarchical tree.

Single left click on a chart when snapped to a waveform.

•

Selects the waveform and the waveform is highlighted on the Hierarchical tree.

Single right-click on a chart when snapped to a waveform.

•

1-4

The right-click marker box is displayed, which allows for placement and removal of Waveform markers and Text markers. It also allows access to full details for that waveform.

2001-0141 Rev. B

AEP/CAEP Introduction

How it works Auditory Evoked Response

Auditory Evoked Potential (AEP) can be used to evaluate the integrity of the auditory system and are used to make inferences about hearing. AEPs encompass a series of neurologic events that travel along the entire length of the auditory pathway – from the cochlea to the auditory cortex. There have been as many as 15 AEPs identified within the first 500 ms post-stimulus onset. In order to identify the neural integrity of the auditory system, it is necessary to consider the size and latency of the response and utilize averaging and stimulus parameters to elicit and isolate the AEP interest. Electroencephalography (EEG) is spontaneous, random electric activity generated in the central nervous system in the absence of stimulation. An evoked potential is an electric response from the nervous system following the presentation of a stimulus. This is a distinct response that is embedded in the spontaneous EEG activity that can be measured and recorded using surface electrodes that are placed on the scalp. When the stimulus is sound, the evoked potential is called an Auditory Evoked Potential. The AEP is a small electric response embedded in the ongoing EEG. Signal averaging is a technique used to isolate the AEP response. It is assumed that the AEP response is synchronous with the onset of a brief acoustic stimulus; therefore, it will emerge in a predictable shape within a specific timeframe of the stimulus. When the Audera averages EEG signal relative to the acoustic stimulus, the AEP response will remain constant, and the random EEG background signal will “cancel” out – leaving the desired AEP response. The stimulus used to elicit an AEP response can be a short duration stimulus or a steady state modulated signal. The AEP is an onset response, a large number of neurons must fire at the same time to identify the response. To ensure this synchronous firing, a short duration stimulus is used. The two most common short duration stimuli are the click and the tone burst (or tone pip). The traditional click stimulus is a 100 μs electrical pulse that has a frequency range of approximately 100 to 10,000 Hz. The broad-band nature of the click provides stimulation of a large portion of the cochlea, which causes a large number of neurons to fire simultaneously. The resulting AEP provides information on the neural synchrony of the auditory nerve. The tone pip (also called tone burst) stimulus assists in the evaluation of frequency specific performance of the auditory system. The frequency-specific stimulus is achieved by presenting a Sine wave for a brief duration. The Audera tone pip stimulus is based on the number of cycles presented. Specifically, the rise and fall times of the stimuli are 2 cycles and the plateau is either 1 or 0 cycles. With this approach, the duration of the stimulus varies with frequency, but the energy content of stimulus is consistent for each frequency. CE-Chirp® is a new broad-band stimulus available on the Audera. The CE-Chirp stimulus has the same frequency response and energy spectrum as the traditional click stimulus; however, it is designed to counteract the temporal dispersion of the travelling wave inherent in the cochlea by presenting the low frequency energy before the high frequency energy. Because the energy reaches all regions of the cochlea at approximately the same time, the AEP amplitude generated has been demonstrated to be 1.5 to 2 times more robust than the corresponding click ABR amplitude in normal hearing subjects. CE-Chirp Octave Band stimuli at 500, 1000, 2000 and 4000 Hz are now available for frequency specific threshold estimation. Designed along the same principle as the broad-band CE-Chirp, the octave-band chirp stimuli elicit optimal waveforms for frequency specific evaluation. A new calibration procedure is required for the CE-Chirp and CE-Chirp Octave Band stimuli. A GSI recommended Special Instrument Distributor or service technician must apply the new calibration procedures for all applicable Audera units.

2001-0141 Rev. B

1-5

AEP/CAEP Introduction

Calibration Procedures

International standards have recently been established to provide values for reference equivalent threshold sound pressure levels (RETSPLs) and reference equivalent vibratory force levels (RETVFLs) for clicks and tone bursts used in Auditory Evoked Potential testing. ISO (International Organization for Standards) 389-6 provides the reference threshold hearing values for test signals while IEC 60645-3 defines how to calibrate click stimuli and the tone burst stimuli. A new calibration scheme has been implemented into the Audera with v2.7 to comply with the requirements of ISO 389-6 and IEC 60645-3. All Audera V2.7 equipment will be shipped with the new calibration files for purchased transducers including TIP 50 ER-3 Insert Earphones, TDH-39 Headphones, and B71 Bone Vibrator. Calibration files are provided for short duration stimuli including the Click, CE-Chirp, CE- Chirp Octave Bands, and Tone Pips of 2-1-2, 2-0-2, 0.5-2-0.5 msec durations for all test frequencies. Note that the B70A Bone Vibrator and the 100 msec Cortical AEP Tone Pip stimuli are referenced to pure tone RETSPL values. When upgrading from a previous version to V2.7, it is necessary to contact a GSI recommended distributor to calibrate current transducers to the new standard.

Impact of New Calibration on Testing

The International Organization for Standardization (ISO) has reference hearing threshold data for specific transducers to promote agreement and uniformity in the expression of results of hearing threshold measurements. The change in calibration does not alter the expected results achieved with Auditory Evoked Potential testing, but does have an effect on the nHL of the signal being presented. When testing pure tone thresholds, the standard HL (Hearing Level) label is used. Because the Auditory Evoked Potential testing stimuli are transient, the label nHL (normal Hearing Level) is the most common method of defining intensity. It is recommended that each facility collect a reference for normal hearing level from a group of normal hearing subject for each new short duration stimulus (Click, CE-Chirp, CE-Chirp Octave Band and Tone-pip). ISO 389-9 provides recommendations for determining reference hearing threshold levels (nHL). In addition to the testing procedures for each transducer, there are recommendations for the test subjects (n=25 males and females between the ages of 18 to 25, normal hearing, normal middle ear function). Threshold testing with a short duration stimuli will produce thresholds that are 20 to 30 dB poorer than thresholds obtained with pure tone stimuli. This stimulus-response behavior explains the approximate 20 dB correction factor in threshold estimation with traditional AEP testing. The new RETSPL values compensate for the difference in thresholds and indicate more accurate threshold estimation. The calibration values are based upon a repetition rate of 20 Hz. New calibration files are required for use with the new CE-Chirp and CE-Chirp Octave Band stimuli. In the event that the user does not want to utilize the new stimuli or the new calibration, the user has the option to continue to use the previous calibration scheme. This may be a desired option for comparing previous test results on a particular patient. The calibration scheme that will be utilized by the Audera v2.7 is determined in the Options > Main Options from the software’s

main screen. When the box “ISO 389-6 (2007)” is checked, the new RETSPL will be applied to all short duration stimuli (Click, CE-Chirp, CE-Chirp Octave Band and Tone Pip). When the box “ISO 389-6 (2007)” is not checked, the previous RETSPLs will be used.

1-6

2001-0141 Rev. B

GSI Audera

Also See: Auditory Brainstem Response in the Appendix.

Electrocochleography

The Typical ECochG response arises from the cochlea and eighth (auditory) cranial nerves and occurs within the first 2 to 3 ms after an abrupt stimulus.

Also See: Application notes in the Appendix in this guide.

2001-0141 Rev. B

1-7

AEP/CAEP Introduction

The Response When utilizing an alternating polarity click, the response is similar to the figure below. Place appropriate labels [Summating Potential (SP), Action Potential (AP) and Base] as indicated. The software calculates the appropriate ratios, which can be compared between ears (interaual asymmetry) or to expected values (if both ears are affected) depending on the electrodes used. Expected SP/AP ratios: TIPtrodes: < 0.5, Extratympanic: < 0.35, Transtympanic: < 0.3

Protocol for ECochG in the GSI Audera – AEP Transducer: Insert Phones Stimulus: 100 µsec click.

Polarity: Alternating Intensity: 95 dBHL Masking offset: -40 dB Repetition rate: 9.1 Hz Filters: 10 Hz to 3,000 Hz Time base: -1 ms to 9 ms Noise rejection: ± 25 µsec For more information on methodology and interpretation please refer to: Margolis, R., (1999) Electrocochleography . Hall, James W. III. Handbook of Auditory Evoked Potentials. “

Electrical Auditory Evoked Potentials

”

Electrical AEP’s occur as described above, but the stimulation is an electrical current delivered to the auditory system typically through a cochlear implant. EABRs are measured in the AEP software application. Also See: Please see the Electrical Auditory Evoked Potentials application note in the Appendix.

Repeatability check

1-8

When using auditory evoked potentials to determine retro cochlear function, consider both internal and external environmental factors, which may influence the accuracy of the test results. A second test is recommended to determine the repeatability of the response.

2001-0141 Rev. B

GSI Audera

Blank page.

2001-0141 Rev. B

1-8

2

AEP/CAEP Screens

Note: The user information contained in this chapter relates to AEP and CAEP applications. For ease when reading, only AEP is written.

2001-0141 Rev. B

2-1

GSI Audera

Blank page.

2-2

2001-0141 Rev. B

AEP/CAEP Screens

Introduction The GSI Audera Main Screen includes the Patient Database as well as access to the Global Options that apply to all applications within the GSI Audera program. Database features include Search Criteria for existing patients, New Patient button, Patient List, and Session Details with the examiner name. Database backup, archive, restore, import, and export patient records are all accessed via the Database menu on the Main GSI Audera Screen. See the GSI Audera Reference Guide for system setup instructions prior to beginning testing in any application and for a detailed description of the items listed above. The GSI Audera Main Screen also contains the Applications buttons to provide access to all licensed software applications. Application buttons become active after a patient has been selected from the database or new patient information has been entered and saved. The following Application buttons may appear at the bottom of the GSI Audera Main Screen: AEP, Cortical AEP, ASSR, and DPOAE. Only those buttons for which a software license has been purchased will be displayed. The AEP application consists of two screens: The Review screen and the Acquisition screen. Depending on the options selected on the GSI Audera Main Screen (Options > Main Options), either the Review screen or the Acquisition screen will be the first screen displayed when starting the AEP application for a new patient. If AEP data already exists for a selected patient, the Review screen will be opened.

2001-0141 Rev. B

2-3

GSI Audera

AEP/CAEP Acquisition screen From the Review Screen Control Panel, select the Acquisition screen button to display the AEP Acquisition screen. Choose between a single screen (Figure 1) or a split screen (Figure 2) display. NOTE: If no data is available, the Review screen will not be displayed. Even if Options > AEP Options to go directly to the Acquisition screen has been selected.

1 2

8 7

3

6

4

5

Figure 1: Single screen AEP Acquisition display.

The single screen is divided into 8 sections

2-4

1.

Menu Bar

2.

Cursor Display

3.

Previous Results Display Panel

4.

Current Acquisition Display Panel

5.

Ongoing EEG display

6.

Acquisition Screen Control Panel

7.

Test Status Display

8.

Communication Status

2001-0141 Rev. B

AEP/CAEP Screens

1 2

8 7

3 6

4

5

Figure 2: Split screen AEP Acquisition display.

The split screen is divided into 8 sections

1.

Menu Bar

2.

Cursor Display

3.

Previous Results Display Panels: Left (Channel 1), Right (Channel 2)

4.

Current Acquisition Display Panel

5.

Ongoing EEG display

6.

Acquisition Screen Control Panel

7.

Test Status Display

8.

Communication Status

1. Menu bar

The Menu bar can be used to change parameters on editable tests, change AEP options and view the GSI Audera User guides.

2. Cursor Display Boxes

These boxes display the X (latency) and Y (amplitude) values as represented by the cursor when marking waveforms. (See Marking waveforms.)

Figure 2: Cursor display.

Figure 3: Cursor display with measurements. Three measurements are available for display and are defined in the Marker Sets measurement tab.

2001-0141 Rev. B

2-5

GSI Audera

3. Previous Results display

After the test result has been accepted, the waveform will appear in either the left or right panel. If the screen is split, left ear results will go to the left panel automatically, right ear results will be placed into the right panel. Clicking within the left or right panel will automatically change the ear designation in the acquisition panel. Waveforms will remain in the display until a new chart is selected on the Review screen. The Zoom button maximizes the chart so that it occupies the whole screen. Clicking Zoom Out returns the screen to its original size

Figure 1: Waveform timescale and gain controls.

Waveform time scale controls The button shortens the time base by half. The button will double the time frame if the time base has already been shortened. The time base cannot be expanded beyond the original collection time base. The

button resets the display to the collection time base.

Vertical waveform scale controls There are four buttons of the acquired waveforms. The

at the top of the selected chart that will change the vertical scale

button allows for manual control of the vertical scale. When

is selected, the

increases the scale while the decreases the scale. All waveforms within a chart will change in scale equally. A scroll bar will appear on the right side of the chart to move the waveforms up and down within the panel. When the waveform scale is increased and the whole waveform is not visible within the chart, the scroll bar can be used to move the chart up and down within the window. button is selected in the chart within the Acquisition screen, new waveforms will go into If the the chart with the current scaling. Placing the cursor on the bottom line of the chart and dragging up or down will increase or decrease the size of the chart window. The button allows for automatic scaling. While scale the waveform to fit within the chart.

is selected, the software will automatically

If the button is selected in the Acquisition screen, new waveforms will be scaled to fit the chart and this may cause the previous waveform scale to change accordingly. The X axis is displayed in ms (milliseconds) and represents the timebase, which is defined by the Test Set parameters. The Y axis is displayed in microvolts uV or uV Abs and represents the amplitude of the waveforms. If the uV Abs Scale is displayed on the Y axis, the ’Grab’ hand is no longer available on the cursor as no movement of the waveforms is possible.

2-6

2001-0141 Rev. B

AEP/CAEP Screens

4. Current Acquisition display

This panel displays the current acquisition or, if the test is paused, the ongoing EEG for either Channel 1 or Channel 2 (depending on the channel selected). If an acquisition is accepted the waveform currently displayed in the panel is transferred to the Previous Results Display above and the current acquisition display is cleared. Accepted waveforms are saved by the system and must be deleted in the review screen to be removed from the patients file. Discarded waveforms are not saved and are no longer available in the patient file. The X-axis is displayed in ms (milliseconds) and is defined by the Test Set parameters. The Y-axis is displayed in uV (microvolts) and indicates the amplitude of the waveform or EEG.

Use AVG Scale

5. Ongoing EEG display

buttons to change the Y-axis scale during acquisition.

This panel contains the ongoing EEG display for Channel 1 and Channel 2. Select which channel to view in the Pause mode by using the radio control buttons to the right of the display. The EEG Scale buttons above the display will change the Y-axis of the EEG display. They change the scale of the current acquisition.

6. Acquisition Screen Control Panel

This panel provides the means for controlling the testing procedure. Select the Test Set, the Test Item and the level for testing. The test is started and stopped using this panel.

Figure 1: Acquisition screen control panel. Test Set - Click the drop-down arrow to display a list of available Test Sets. Test Item - Click the drop-down arrow to display a list of available items within the selected Test Set. The item.

2001-0141 Rev. B

arrows can be used to move backward (left arrow) or forward (right arrow) to a test

2-7

GSI Audera

Details - Click

to display full details of the currently selected Test Item.

Figure 2: Test Details panel. Click on the buttons while the Test Details window is open to view details for other items in the selected Test Set. dB - The

buttons can be used to increase or decrease the output dB level. Clicking on

the button increases the dB output by 5 dB. Clicking on the by 5 dB.

Note: Holding down the Ctrl key and clicking dB Up increments.

button decreases the dB output

will raise the stimulus in 0.5 dB

The maximum level that can be reached is specified by the artificial audio level limit selected from the Options > Main Options menu item on the GSI Audera Main Screen.

!

This Warning symbol indicates a stimulus level of 95 dB SPL or greater has been selected for the current test.

Note: Holding down the Ctrl key and clicking dB Down will lower the stimulus in 0.5 dB increments. The minimum level that can be specified is –10 dB. When -10 dB is selected, there is no stimulus output.

2-8

2001-0141 Rev. B

AEP/CAEP Screens

Ear - Select the stimulus presentation ear and recording channel by clicking on the circle (radio button) before Left (blue) or Right (red). The button will fill with a black dot to indicate which ear is selected. Start One Test - Click to start manual testing using the Test Set and test item displayed. Start Auto Test - Click to start automatic testing using the Test Set and test item displayed. Back to Review - Closes the AEP Acquisition screen and returns to the Review screen, saving any acquired waveforms. Test Impedance - Opens a window that displays active impedance values for both channels. Select Close to return to testing. Avg. - These buttons are used to adjust the Y-axis display gain of the current acquisition chart. EEG - The EEG Up and Down arrows changes the Y-axis on the ongoing EEG display.

2001-0141 Rev. B

2-9

GSI Audera

Changes to Acquisition screen control buttons The Start One Test button and Start Auto Test button will appear grey if the hardware is not connected. When the Start One Test button has been selected, the Start Test button and the 3 buttons below it change designations. The Start One Test button is renamed Stop Test and is used to terminate the test. During Auto Test, the next test item will start. The Back to Review Screen is renamed Pause, selecting Pause will stop averaging, displaying raw EEG in the current acquisition display. The Test Impedance is renamed Extend and is used to extend the test beyond the defined number of sweeps.

7. Test Status display

This area indicates the test status during and after acquisition.

Figure 1: Test Status display. Test state - Indicates test status, Ready or Test Complete. Test time - When acquisition is started, this box displays the time remaining, time exceeded (negative numbers) or Done if the test is complete. Sweeps - Displays the total number of sweeps. Rejects % - Displays the rejected sweeps as a percentage of total sweeps. Reject # - Displays the total number of rejected sweeps.

8. Communication Status

2-10

This area displays communication information during data acquisition. During data acquisition a symbol will appear in the upper left corner of the menu bar and indicates motion to show that data acquisition is in progress.

2001-0141 Rev. B

AEP/CAEP Screens

AEP/CAEP Review screen Note: The following information relates to AEP and CAEP, but for ease when reading these instructions, ONLY AEP is written. Any differences between the AEP application and the CAEP application will be defined in the relevant section with an addendum.

6 1 2 5 3

4

Figure 1: The AEP Review Screen

The AEP Review Screen is divided into 6 sections

2001-0141 Rev. B

1.

Menu Bar

2.

Toolbar

3.

Left and Right Chart Panels

4.

Hierarchical Tree

5.

Review Screen Control Panel

6.

Cursor Display/Measurement Display

2-11

GSI Audera

1. Menu Bar

Patient > Edit Opens the Patient Details screen of the current patient for viewing or editing.

•Select Save to save any changes and close the patient details window. •Select Cancel to close the window without changes.

Patient > Print current chart Select this option to print the chart. Prior to selecting this option, select the desired chart from the Hierarchical Tree or click on the chart in the panel. If no chart is selected, this option is unavailable.

Patient > Print AEP Report This option will display an AEP Report Selection dialog box. This dialog box lists all charts saved for the right and left ears and allows for the creation of customized reports. (See Printing an AEP Report for more details.) Note: The top chart from the left panel and right panel are selected as default.

Patient > Back to Main Screen Returns to the GSI Audera Main Screen

Test > Edit AEP/CAEP Test Set Displays a dialog box enabling the ability to add, change or delete items within Test Sets, or if required, entire Test Sets. Test Sets using parameters typically used by many clinics have been provided in a READ ONLY format. To facilitate the creation of new Test Sets, Test Sets supplied with the GSI Audera system (which cannot be edited) may be copied, renamed, and then edited as desired. (See Creating Test Sets for a more detailed explanation.)

Tests > List AEP Test Sets Provides a scrollable window displaying all AEP Test Sets. Full details are provided for each Test Set. As a precaution against accidental change or loss, Test Sets supplied with the GSI Audera system are provided in a READ ONLY format and cannot be deleted or modified. However, they may be copied, renamed and then changed to form new Test Sets.

2-12

2001-0141 Rev. B

AEP/CAEP Screens

Options > AEP Options

Master units The software can be set to use the following units:

•dB nHL • dB pSPL The currently selected units are called the Master units. The default Master units are dB nHL. The Test Set Editor and the Test Details window will display all units, at the respective equivalent levels, to those of the selected master units. Mixed units within a session are not permitted. The software will display a notification if an attempt is made to mix units within a session. It is possible to change the units temporarily while the session is still open or to permanently change the units by changing them in the Options menu. Graph options

• The charts in the Review screen and the Acquisition screen can be displayed with or without grid lines. The default is disabled for the Review screen and enabled for the Acquisition screen.

•The number of waveforms that can be stacked vertically in each chart can be selected. The default is set at 8, a value from 8 to 50 can be selected.

• Use Blue/Red. A checkmark in this box indicates waveforms will be color-coded. Blue for the left ear and Red for the right ear. No checkmark in this box disables color coding.

•Split acquisition screen left/right. When this box is checked, in the Acquisition screen the left ear results will be displayed on the left side and the right ear results will be displayed on the right side of the screen. To have all results displayed in a single panel, uncheck the split acquisition option.

2001-0141 Rev. B

2-13

GSI Audera

Auto Test Delay The delay between each test in the Auto Test Set sequence can be altered as required. The default is set to 2 seconds, but from 1 to 15 seconds can be selected. During this delay, the clinician has time to review the acquired data. Beep at trial end A checkmark in this box will cause the keyboard bell to sound at the end of each trial. This box is unchecked by default. Note: Loudness of the keyboard bell may vary with the computer model and settings.

Click OK to apply changes to AEP Options.

Options > Default Spread Settings Waveforms can be spread apart automatically as they are placed on the chart after each trial.

Figure 1: Spreading preferences. Selecting Default Spread settings affects only newly created charts and will determine the layout of waveforms within a chart as they are acquired. There are two types of spreading, None or Fixed Offset. If None is selected, no spreading is used and the waveforms are overlaid on top of each other, sorted in descending order by stimulus intensity. The Y-axis scale is displayed in absolute units. The waveforms cannot be repositioned, and the ’Grab’ hand on the cursor is not active. All check boxes are now inactive. If Fixed Offset is selected, the waveforms are spaced by a fixed amount. The default is set to 0.30 uV. The Y-axis scale is displayed in relative units. There are several options for grouping the waveforms using the checkmark boxes.

2-14

2001-0141 Rev. B

AEP/CAEP Screens

Note: Changing the spread of already acquired waveforms is not possible using the Options > Default Spread Settings option. To change the spread settings on previously acquired charts, right-click on the Hierarchical Tree in the Review screen and select the desired spreading options. Alternatively, click on a chart within a panel and select the Spread Settings toolbar button. The spread settings window will appear. Select the desired spread options and select OK to close the window. Likewise, if a Fixed offset was selected in Options > Default Spread Setting, this can be removed in the same manner.

If all options are Unchecked, the waveforms for the Left and Right ears are overlaid and sorted by level. Group results for left and right ears together Check this option to separate left and right ear waveforms into groups. Overlay results recorded for the same level and ear Check this option to overlay waveforms collected with the same level and ear. The Y-axis scale is an absolute measurement. The “Grab” hand on the Cursor is not active and waves cannot be moved. This only applies when all waveforms are at the same intensity level, when more results are acquired at different intensities, the scale becomes relative and the “Grab” hand on the cursor is restored, allowing waves to be moved vertically within the chart. Overlay Ipsi and Contra results for the same level and ear Check this option to overlay the Ipsi and Contra results for the same level and ear. Click OK to apply any changes made. Click Cancel to close the window and return the settings to previously saved settings. Clicking on Program Defaults will return any changes made to the spread settings to the GSI Audera default settings.

Options > Edit Marker Set Displays the Markers, measurement and reference data for all marker sets and allows new marker sets to be created. (See Markers for more details.)

Help > About Audera Provides information about the software, including the version number.

Help > Contacting GSI Provides information on how to contact GSI.

Help > View Manual Provides a full set of manuals, which can be opened and minimized while testing without having to exit from the GSI Audera.

2001-0141 Rev. B

2-15

GSI Audera

2. Toolbar buttons

There are multiple ways to review and analyze data from the Review screen. The Hierarchical Tree right-click menu, the corresponding keyboard Function Keys, and the Toolbar buttons can all be used for data manipulation.

The item selected in the Hierarchical Tree determines which Toolbar buttons, Function Keys, and right-click menus are available. The toolbar buttons provide functions affecting the selected panel, chart, or waveform.

Hide Temporarily hides the selected chart or waveform from the screen. Alternatively, select the Insert key to achieve the same results. If all waves in a chart are hidden, the empty chart will no longer be displayed. Click on the chart in the hierarchical tree and then click the Hide button to display the waves again. It is not possible to retrieve individual waves once the chart has been hidden without first displaying the associated chart. Hidden charts or waveforms are preceded by the designator (h) in the hierarchical tree.

Delete PERMANENTLY removes an individual wave, a single chart or all charts within a panel from the Review screen. The Delete key on the keyboard can also be used to delete waveforms, charts or panels in the same way. Deleted results cannot be retrieved.

Copy Copies an existing waveform or chart. An individual waveform will be copied into the existing chart, a copied chart will be displayed at the bottom of the panel. The result of the copy will be labeled in the Hierarchical Tree as "T# copy...”.

Spread Settings This option is used to spread waveforms within a chart by a fixed amount, the amount can be adjusted. Select a chart to be spread and then select this button to reveal the Set Chart Spread Settings window. The spread can be adjusted in the window, but applies only to the currently selected chart.

2-16

2001-0141 Rev. B

AEP/CAEP Screens

Invert Chart Inverts an individual waveform or a chart. Inverted waveforms are designated by a checkmark in the right-click menu of the hierarchical tree.

Smooth Smoothes the peaks of the waveform by decreasing the number of points in the display. There is no change to the raw data waveform. There are three levels of smoothing available. 1. 2. 3.

Click on the Smoothing icon to take a 3 point average. The waveform will display S3. Click the icon again to take a 6 point average. The waveform will display an S6 on the left hand side of the chart. Click on the icon again to take a 9 point average. An S9 will appear on the chart.

A single waveform can be smoothed out by selecting the trace on the chart or within the hierarchical tree. To smooth all the waveforms within a chart, click anywhere in the chart or select the chart from the hierarchical tree. There is a maximum of 9 point smoothing. Selecting the Smooth icon one more time will return the waveform/chart to its original raw data form.

Rename Renames the selected item. Type in new name and click OK.

Print Chart Opens the Print Preview dialog box, which prints the selected chart.

Color Changes the color of an individual waveform or a chart. It is not possible to recolor a whole panel. For a chart, choose Blue / Red to match Left / Right, or the waves maybe multicolored. Use the radio button to select multicolored, then click OK to apply the color change. Each wave within the chart will have a different color. A list of the colored waves details will be displayed below the chart. This list can only display the first 10 waves on the chart with their relevant color and test details.

Reset Resets the size and display parameters of the selected item to the value used during acquisition.

2001-0141 Rev. B

2-17

GSI Audera

Measurement Chart This option is used to display measurement values associated with an individual marked waveform or the Latency vs. Intensity graph for a selected chart.

Figure 1: Measurement chart.

Patient History Displays the Patient History dialog box, which is used to review, add, copy, or print notes in the patient files.

Add Notes Displays the Enter Note dialog box. Each note entry is date and time stamped. Note: All notes entered in the Patient History are non-editable. They are date and time stamped at each entry.

3. Left and Right Charting Panels

2-18

When a chart is selected in the review screen, data in the acquisition screen will go directly into the selected chart. It is possible to view data from both ears in the same chart on the Review Screen by relocating waveforms within charts. This is accomplished by clicking and dragging items from within the Hierarchical Tree.

2001-0141 Rev. B

AEP/CAEP Screens

4. Hierarchical Tree

Figure 1: Hierarchical tree. The Hierarchical Tree is a representation of all the data acquired and is displayed in a structured manner. By double-clicking on the white background, the tree window will be enlarged to allow easier viewing of the display. A hierarchy is displayed within this tree; each panel contains charts and each chart contains waveforms. It is possible to modify/analyze the properties of the displayed items, whether it is a panel, chart or waveform by right-clicking on that item in the Hierarchical Tree. This will display a list of options with corresponding keyboard function keys.

Figure 2: Function list and corresponding keyboard function keys. Not all functions are enabled at all levels of the hierarchical tree. Those that are gray are not available at that level. For example, there are only 3 functions available for panel modification/ analysis, but all functions are available to modify/analyze a chart. The modification/analysis is also possible by left clicking on the panel, chart or wave to be modified, then using the Toolbar function buttons. Each waveform is given a T number for identification. When any change is made to a waveform (e.g., copy, add, subtract etc.), a new T number is assigned to the resulting waveform along with the T numbers from the original waveform(s) and the analysis applied.

2001-0141 Rev. B

2-19

GSI Audera

5. Review Screen control panel

Figure 1: Review screen control panel. Back to Main Screen - This button returns to the Main Screen, saving any tests that have been performed. Test Impedance - This button provides a means of monitoring the electrode impedance on the screen. Select the Test Impedance button to display the Impedance Test Window before or after a test.

Figure 2: Impedance test panel. This window displays a bar graph representation of each of the amplifier inputs. Each input is compared to the common electrode and the resulting impedance is displayed for each input in sequence. Each process is displayed for approximately 2-3 seconds before proceeding to the next input. This process continues until the Close button is selected. This provides the opportunity to manipulate or reapply electrodes to obtain satisfactory impedance values. Color coding is used as well as a numeric range to indicate the impedance ranges. IMPORTANT: Ideally, the impedance should be below 5K ohms.

Acquisition Screen - Click this button to display the Acquisition screen. (This screen is described in more detail in AEP Acquisition screen.)

2-20

2001-0141 Rev. B

AEP/CAEP Screens

6. Cursor Display/ Measurement Display

The two boxes shown in Figure 1 below display the cursor crosshair position on the current waveform. The first box indicates the X-coordinates (Latency) of the cursor and is measured in milliseconds. The second box is measured in microvolts and represents the Y-coordinates of the cursor.

Figure 1: Cursor position display.

Figure 2: Measurement display. When a marked waveform is selected, the measurements for the waveform are displayed on the menu bar above the control panel. To select the measurements that will be displayed, see the next chapter Reviewing and Analyzing AEP Data > Markers.

2001-0141 Rev. B

2-21

GSI Audera

Blank page.

2-22

2001-0141 Rev. B

3

Performing AEP/CAEP Tests

This chapter describes how to perform AEP/CAEP tests.

2001-0141 Rev. B

3-1

GSI Audera

Blank page.

3-2

2001-0141 Rev. B

Performing AEP/CAEP Tests

Prepare the system BEFORE attaching earphones or electrodes to a patient, ensure that the system is powered on and ready for use and the software is running.

! WARNING Never switch the power on to either the computer or the GSI Audera unit when the system is attached to the patient.

Prepare the patient A variety of attachment methods are favored by different clinics. However, the following guidelines should be followed:

• Lightly clean the skin with a skin prepping gel. • With reusable electrodes, apply a conductive gel or paste and attach the electrode firmly with tape. Disposable electrodes generally incorporate their own conductive gels.

• The 4 electrodes should be attached as shown in Figure 1. The high forehead electrode should ideally be placed as close to Cz as is possible (Cz is located at the vertex of the head); with newborns this is often difficult due to the softness of the skull around that area. It is therefore advisable to attach the high forehead electrode as high as it is comfortable and safe to do so. Attach the other three electrodes as outlined in the diagram. Note that left and right electrodes can be attached to earlobes or mastoids.

• Plug the electrodes into the amplifier. • Check the electrode impedance.

Jumper between 1+ and 2+

1+ or 2+ High forehead CH

Common Low forehead

+1

_

GND

Audera

Right earlobe 2-

1- Left earlobe

CH

+2

_

TM

Amplifier

> 50 20 - 50 10 - 20 5 - 10 K 2-5 AEP Options menu. The default is set to 2 seconds.

2.

Select the ear to be tested.

3.

Select the Test Set from the Acquisition screen control panel.

4.

Click on the Auto Test button.

Auto testing can still be controlled manually if required. The Stop Auto Test, Pause/Continue and Extend buttons are functional during Auto Test. The Discard/Accept buttons are disabled because ALL test results are accepted during the Auto Test. When the Start Auto Test button is selected it is renamed to Next Test. The Auto Test will advance through all items in the Test Set after meeting the criteria for accepted number of sweeps for each test set item. Each trial is saved automatically as the criteria is reached and is transferred to the Previous Results section of the window. Select the Next Test button at any time during acquisition to stop the current acquisition and advance to the next test set item in the list. The current acquisition will be saved automatically and transferred to the Previous Results window at the top of the Acquisition screen. A new acquisition will begin with the next item in the Test Set. Selecting Stop Auto Test will stop the Auto Test procedure before completion if required. Reselecting Start Auto Test will reset the Test Set back to item number 1 in the list. The Auto Test Procedure will test the ear selected. 5.

To test the other ear, follow steps 2 to 4 above.

For each test set item, the stimulus is always limited to the “Artificial Audio Level limit” set in Options > Main Options. The Test Set Editor is accessed from the Tests > Edit AEP Test Sets menu item on the Review screen. It is used to create a new test set or edit an existing Test Set.

2001-0141 Rev. B

3-7

GSI Audera

Creating Custom AEP Test Sets The Test Set Editor is divided into 3 main areas: 1.

Test Set

2.

Test Item

3.

Function Keys

1

2

3 Figure 1: AEP Test Set Editor. Note: There are differences between the AEP and CAEP Test Set Editor. These are identified with bold, underlined text.

1. Test Set

This section is comprised of 5 drop down menus, 4 checkboxes and 5 buttons.

Test Set name - The drop down menu displays a list of Test Sets within the GSI Audera system. There are several default AEP Test Sets supplied with the system. These Test Sets cannot be changed or deleted, but new Test Sets can be created using the Copy and Edit, or Add options. Note: There are default CAEP Test Sets supplied with the system. Test Sets have been provided for use in Middle Latency and Long Latency. These Test Sets cannot be changed or deleted, but new Test Sets can be created using the Copy and Edit or Add options.

3-8

2001-0141 Rev. B

Performing AEP/CAEP Tests

Stimulus - Select the transducer for Ipsilateral stimulation. There are three transducer options available: Insert/ Headphones, Bone Vibrator, and Loudspeaker. (When selecting Insert/ Headphone as the transducer ensure the correct calibration file is selected in Main Screen Options > Assign Calibration Information.) Masking - The Masking window reveals the three transducer types available for Contralateral Masking Stimulation: Insert/Headphones, Bone Vibrator and Loudspeaker. There are some combinations of Stimulus Transducer and Masking Transducer that are not acceptable. The table below defines the availability of the combination pairs. Stimulus Transducer

Masking Transducer

Allowed

Not Allowed

Insert/Headphones

Insert/Headphones

X

Insert/Headphones

Bone Vibrator

X

Insert/Headphones

Loudspeaker

X

Bone Vibrator

Insert/Headphones

X

Bone Vibrator

Bone Vibrator

X

Bone Vibrator

Loudspeaker

X

Loudspeaker

Insert/Headphones

Loudspeaker

Bone Vibrator

X

Loudspeaker

Loudspeaker

X

X

Masking type - The Masking type options are Absolute Value or Stimulus Relative.

• If Absolute Value is selected for masking type, the Masking level display will allow the masking to be set to an absolute level. This level will not change even if there is an increase or decrease in stimulus level.

• If Stimulus Relative is selected for masking type, the Masking offset display (previously masking level) can be set to allow the intensity of the masking to vary relative to the stimulus intensity presented. Marker Set - Select the Marker Set for this Test Set. The AEP application is provided with 4 default marker sets. New marker sets may be created, if required (see section Defining a New Marker). Note: The CAEP application is provided with 3 default marker sets. New marker sets may be created. (See Defining a new marker set). Any new marker sets created in this section will be available for selection as a global parameter in the marker set window. Use noise checking - Rejects sweeps above the defined noise rejection voltage when enabled. Random test mode - Check this option to present Test Items in a random order when using the Auto Test Mode.

2001-0141 Rev. B

3-9

GSI Audera

Use both EEG channels - Enable both EEG channels to allow the recording of ipsilateral and contralateral waveforms. If this box is not checked, only the ipsilateral channel will be used. The left ear is assigned to channel 1 and the right ear to channel 2. External Trigger - Check this box to enable the external trigger for Electrical ABR (EABR) testing. When the external trigger is enabled, the GSI Audera system is used to record activity that is generated by an electrical stimulus presented via proprietary cochlear implant software programs. The external trigger selection box should be used only for EABR Test Sets. When the external trigger is enabled, a separate cable is used to deliver an electrical stimulus to the patient’s cochlear implant. The stimulus is defined in the cochlear implant software. Therefore, the Test Set Editor in the GSI Audera software is not used to define the stimulus parameters. Stimulus rate, polarity, etc., may be set to any value within the GSI Audera software. Contact the manufacturer of the cochlear implant software for specific instructions on using software for EABR testing. Note: AEP Test Sets for patients without cochlear implants should never use the external trigger option. The Function keys Add, Delete, Copy and Edit, Rename and Lock are used to make changes in Test Sets. Add - Click to add new Test Sets. All parameters within the new Test Set are set to the System defaults. Delete - Click to delete Test Sets. This Function key is not available for Test Sets designated as READ ONLY. Copy and Edit - Click to create an exact copy of an existing Test Set, which is available for editing. Rename - Click to rename a Test Set. This function key is not available for Test Sets designated as READ ONLY. Lock - Click this button to Save the Test Set as Read Only. When a test set is saved as Read Only, it is no longer possible to make changes to the Test Set. To be able to modify any parameters within the Test Set at a later date, do not click the Lock button before closing the Test Set Editor.

IMPORTANT: It is not possible to delete or rename any of the default Test Sets provided with the GSI Audera System. The items below are only available to edit when a test set has been copied or added.

• • • • • • • •

3-10

stimulus type, polarity and level masking level / masking offset nHL adjustment repetition rate total sweeps high and low pass filtering (see filters) display window start time and end time noise rejection level and start time 2001-0141 Rev. B

Performing AEP/CAEP Tests

2. Test Item

Stimulus Polarity - Select the desired stimulus polarity. Stimulus Level - This indicates the default level at which the stimulus is presented in any given Test Item (-10 to 130 dBnHL). The stimulus level of a Test Item can be changed by using the Item list in the Acquisition screen.

and

buttons below the Test

Masking Level - The value selected in this window is fixed. Masking level is displayed in the Test Item list if Absolute value was selected as the Masking Type. Masking Offset - The value selected in this window allows the masking to change relative to the stimulus presented. (e.g., if the offset is -35 dB, the intensity of masking will always be 35 dB below the stimulus intensity level.) Masking Offset is displayed in the Test Item list if Stimulus Relative was selected as the Masking Type. nHL Adjustment - This field is used to change the dBnHL value based on data collected in the clinic if different from the default value of 0 dBnHL. For a 100 ms click, the GSI Audera default 0 dBnHL value is 25.8 dB pSPL. If the average threshold for a click for a group is determined to be 30 dB pSPL for normal listeners, the nHL adjustment should be set to 4.2. Conversely, if the average threshold is 22 dB pSPL, the adjustment should be set to –3.8. This must be done for all items within the Test Set. The nHL adjustment value will be added to or subtracted from the actual output of the system. Repetition Rate - Selects a repetition rate suitable for the Test Set. The exact rate is displayed adjacent to this box. Repetition rates can be set from 8 Hz to 100 Hz. In AEP only, as the repetition rate increases there will be a slight decrease in pSPL to account for the temporal integration of the stimuli (based on a 100 ms time constant). Increasing the repetition rate from 10 Hz to 100 Hz will create a decrease of less than 10 pSPL. Note: CAEP Repetition rates can be set from 0.2 Hz to 10 Hz. Total Sweeps - Selects the total number of sweeps required. The number of sweeps selected depends on the sub-average size (e.g., for a sub-average size of 34, the total Sweeps display will increase in steps of 34). It is possible to increase the total number of sweeps while in the Acquisition screen by clicking Extend. Sub-average Size - This display may not be changed directly. The value within the display is defined by the repetition rate chosen, rounded UP to next whole number. High and Low Pass Filtering - Filters are set to remove unwanted frequencies from the data collected (e.g. if filters are set with values of 150 Hz to 3 KHz, all frequencies below 150 Hz and above 3 KHz will be filtered out). Note: CAEP Filters - Different filter options are available in CAEP than in AEP. Display window start time and end time - A negative value in the start time display will start the averaging before the stimulus presentation. The end time denotes when averaging stops. The range is dependent on the repetition rate selected.

2001-0141 Rev. B

3-11

GSI Audera

AEP Start and End Time (Timebase) - Depending on the repetition rate selected, the timebase may be from –5 ms to 120 ms. CAEP Start time and End Time (Timebase) - Depending on the repetition rate selected, the timebase may be –50 ms to 1950 ms or 0 to 2000 ms. Noise Rejection level and Start Time - This level denotes the highest value of the signal accepted for averaging, any signal above this value is determined as noise and rejected. The start time defines when the noise rejection level is initiated. The noise rejection default is typically set to ±25 uV, for AEP Test Sets and ±50 uV for CAEP+ AMLR Test Sets with a start time of 1 ms. Sensitivity - The sensitivity setting controls the degree of amplification that will be applied to the input signal by the amplifier system. However, in a digital acquisition system like the GSI Audera, where a high level A-D converter is employed, the sensitivity setting effectively controls the ‘dynamic range’ of the system. In order to acquire the best quality signals possible, for any type of data acquisition, the sensitivity should be set such that the required signal occupies as much of the available dynamic range as possible. For example, when acquiring a small physiological signal such as an Auditory Evoked Potential (AEP), the sensitivity value should be set to a low value, making the system more sensitive. This ensures that the small AEP signals will be resolved as accurately as possible by the A-D converter. The GSI Audera includes default test sets for various test types with appropriate sensitivity settings pre-defined for testing convenience.

3-12

2001-0141 Rev. B

Performing AEP/CAEP Tests

3. Function keys

Save All - This button allows parameter changes to be saved. Cancel - This button will close the Test Set Definition window, returning to the Review screen without applying changes.

Creating a new Test Set 1.

Click the Add button to the right of the Test Set Name Field. The Add Test Set dialog box is displayed.

2.

Enter the name of the new Test Set and click the OK button. The new name will appear in the Test Set name display. It will also be displayed in the Test Set control panel in the AEP Acquisition screen.

3.

Click the Add button to the right of the Test Item field to add a Test Item. The program’s internal defaults values are entered in each field. These can be changed as required.

4.

Enter the desired values for all test parameters (available ranges are shown in brackets to the right of each display) using the Up and Down arrows on the screen or the keyboard.

5.

Repeat the previous steps adding new Test Items, until the required Test Set is defined. The number of items in the Test Item list increments when a Test Item is added.

Note: As each new Test Item is added, the previous Test Item values are displayed into the respective entry boxes. This allows for quick modification of the new Test Item. 6.

Click Save All to save the newly created Test Set. Click Cancel to return to the Review screen with no changes saved.

Note: It is advisable to Lock the new Test Set before saving it to ensure no accidental changes are made. Once the Test Set is locked, it cannot be altered. Do not lock the Test Set if there is any possibility of changes to be made in the Acquisition screen.

2001-0141 Rev. B

3-13

GSI Audera

Editing an existing Test Set 1.

Select the Test Set to edit from the drop down Test Set list.

2.

Click on the Copy and Edit button to the right of the Test Set name field. The Clone Test Set dialog box will be displayed.

3.

Enter the name for the new Test Set and click the OK button. The parameters for the original Test Set will be displayed for all Test Items (It is now possible to Edit these items.)

4.

Edit the parameters in the drop down display fields below the Test Set name. These are global parameters and will apply to all Test Items within the Test Set. Check any or all of boxes in the Test Set display to activate noise checking, initiate random test sequence, etc.

3-14

5.

Select a Test Item to be edited from the drop down list.

6.

Edit the parameters for each test set item as required.

7.

Add or Delete test items as required.

8.

Click Save All to save the newly edited Test Set.

9.

Click Cancel to return to Review Screen with no changes applied.

2001-0141 Rev. B

Performing AEP/CAEP Tests

Filters Digital versus analog

• Analog filters are implemented in the GSI Audera amplifier hardware. • Digital filters are implemented in the GSI Audera software. They are highly repeatable and accurate. Note: GSI Audera uses primarily digital filtering rather than analog filtering.

Linear phase versus nonlinear phase

Linear phase filters delay all frequency components passing through the filter by the same amount and therefore are highly desirable. Nonlinear phase filters delay different frequency components by different amounts and introduce phase distortion:

• Digital filters can be either linear or nonlinear in their phase characteristics. • Analog filters are always nonlinear in their phase characteristics. It is often suggested that all digital filters possess linear phase characteristics. This is incorrect. Most digital filters generally have nonlinear phase characteristics and, therefore, introduce phase distortion. In practical terms, phase distortion is manifested by changes in the measured waveform latencies and changes in the waveform morphology and is dependent upon the type of filtering applied to the raw EEG.

Low pass filters

High pass filters

The GSI Audera AEP system uses digital linear phase filters for the low pass filters. This may result in the measured latencies being shorter than expected. The difference can be as high as 0.2 msec. The difference is due to the deficiency in the characteristics of the nonlinear phase analog filters traditionally used. Latencies measured using these filters are seen to be longer than is actually the true case. The GSI Audera AEP system uses digital nonlinear phase filters for the high pass filters. Phase distortion of the lower EEG frequencies by the high pass filter is less of a problem for AEP measurements than is distortion of the higher EEG frequencies by the low pass filter. The clinician is more interested in the higher EEG frequencies, which tend to form the peaks being measured. If required, phase distortion can be minimized by selecting a high pass filter with the lowest roll off per octave as possible, consistent with good results and with a cut off frequency lower than required, for the evoked potential being detected. Be aware that there is a tradeoff between low phase distortion and optimal signal-to-noise ratio using the filters supplied.

High pass filters set to “No high pass digital filtering” Be aware that if “No high pass digital filtering” is selected in a test item, then the high pass filtering will be determined solely by the GSI Audera amplifier analog filters, not by the software, when using that Test Item. This setting may result in the EEG waveform being superimposed on a DC offset. In some cases this will trigger the noise rejection system and no result will be returned. This setting is NOT recommended and is provided primarily for manufacturing test purposes.

2001-0141 Rev. B

3-15

GSI Audera

Blank page.

3-16

2001-0141 Rev. B

4

Analyzing AEP/CAEP Tests

This chapter describes how to analyze and print AEP/CAEP results.

2001-0141 Rev. B

4-1

GSI Audera

Blank page.

4-2

2001-0141 Rev. B

Analyzing AEP/CAEP Tests

Reviewing and analyzing acquired data AEP data may be reviewed and markers may be placed on waveforms in both the Main AEP Review screen and in the Previous Results Display of the Acquisition screen. Note: Some data analysis functions, including combining waveforms may only be performed in the Review screen.

Figure 1: Review screen. The Review screen, as shown above, may contain multiple charts and each chart may contain several waveforms. There are many options available for displaying the data on the Review screen. Waveforms may be moved, combined, copied or hidden to display the results as required. These options are accessed in one of two ways:

2001-0141 Rev. B

1.

Using the Toolbar buttons at the top of the Review screen.

2.

Using the right-click menu function on the Hierarchical Tree.

4-3

GSI Audera

Markers The Test Set used for acquiring waveforms determines the Marker Set that is available when analyzing the waveforms. There are two methods for placing markers on the waveforms. When placing markers on a waveform, the keyboard number keys correspond to the Marker Set as defined in the Test Set used.

Placing markers on a waveform

1.

Click on the waveform in the chart to select the waveform to be marked or click on the waveform label in the Hierarchical Tree.

2.

Position the cursor at the location on the waveform to place a marker. The Left and Right arrows on the keyboard may be used to position the cursor more precisely. If the Ctrl key is pressed while holding down the Arrow keys, the cursor will move along the wave more quickly.

3.

With the cursor located at the desired position, right-click the waveform to reveal the available marker labels.

4.

Highlight the desired marker label and click to select and place the marker on the waveform. Alternatively, after positioning the cursor, another marker can be placed by selecting the keyboard number that corresponds to the marker label. The numbers 1-9 on the keyboard are allocated for the markers. The number for each marker may vary depending on the Marker set specified.

5.

Moving markers

Repeat these steps until all desired markers have been placed on the waveform.

Markers can be repositioned at any time. Place the cursor at the new location and select the marker label from either the right-click menu or by selecting the keyboard number that corresponds to the marker label. It is not necessary to delete the original marker before repositioning it.

Deleting markers

Markers can be deleted at any time. Place the cursor on the waveform that contains the marker to be removed. Right-click to reveal the marker window and select Remove Marker. A list of all markers that have been used will appear. Select the marker to be remove from the list. The marker label will be removed from the waveform.

4-4

2001-0141 Rev. B

Analyzing AEP/CAEP Tests

Text markers

It is possible to place a text marker on a waveform to provide a note specific to the waveform. For example, if two waveforms with different parameters are acquired into the same chart, it is possible to assign a text marker to each waveform to designate the differences. These markers have no other purpose than to add comments to a waveform and do not have associated reference data.

To place a text marker 1.

Follow the steps for placing markers using the right-click menu and select Text Marker from the list of available markers.

2.

Enter a comment in the display and select OK to place the text on the waveform. When positioning the cursor to place a text marker, ensure the location of the text marker will not obscure other markers on the waveform.

To Create a New Marker Set There are several default AEP Marker Sets provided with the GSI Audera system. These Marker Sets may not be deleted, but it is possible to make an unlimited number of new Marker Sets. Marker Sets are accessed from within the AEP / CAEP Application. Note: There are default Marker Sets provided with the CAEP Application. 1.

Name the New Marker Set. a. Select Options > Edit Marker Set from the Menu Bar. The Edit Marker Set dialog box will be displayed.

Figure 1: Edit Marker Set dialog box. b. In the Edit Marker Sets dialog box, click the Add New Marker Set tab. This will display the Marker Set Name Box. c. Enter a name for the new Marker Set. d. Click ADD. The name entered will be displayed as a new tab in the table. The Markers tab in the definition window will be selected. 2.

Define the Markers. a. Click Add at the bottom of the screen to create a marker label. A Marker Name Box will appear. b. Type in a name (up to five characters) for the first marker label definition.

2001-0141 Rev. B

4-5

GSI Audera

c. Click Save to save the marker label or Cancel to return to the Edit Marker Sets dialog box without saving the marker label. d. Click Add to create another marker label and type in the name for the second marker label. e. Continue adding marker labels until all desired marker labels have been named. f.

Up to 9 marker labels may be defined for each Marker Set. Each marker is assigned to a number key on the keyboard depending on the order in which it appears in the marker list.

g. To move a marker in the list, click the marker label and click Move Up or Move Down to relocate the marker. The location of the marker on the list is important. The markers correspond to the numbers 1-9 on the keyboard from the top of the list to the bottom. For example, if wave IV is placed 6 on the list, this will correspond to the number 6 on the keyboard. th

h. When all marker labels have been entered in the required order, click the Measurements tab. 3.

Define the Measurement Section of the Marker Set

The last step in defining a Marker Set is assigning measurements to the marker labels that have been identified above. Each marker can have one or more measurements associated with it. a. Click Add to display the Measurement dialog box (Figure 1). b. Type in a Measurement Name (e.g., I Latency) of up to 12 characters for the first measurement to be defined.

Figure 1: Measurement Dialog Box. c. Select the Measurement Type. The measurement type selected will define the calculation required to achieve that measurement, and the measurement display will change dependent on the selection. For example, if Peak Latency is selected as the Measurement Type, there will be a prompt to select the marker label to apply this measurement. Alternatively, if Peak to Peak Interval was selected as the Measurement Type, there will be a prompt to select the two marker labels to use in the calculation. d. Enter the necessary information as prompted by the measurement box(es). e. To include the measurement in printed reports, check the box Measurement appears on printed reports. To display the measurement on the Review screen toolbar, check the box Measurement appears on Review screen toolbar. f.

When all information has been entered for the first measurement, click Save. This will place the required measurement details in the measurement screen.

g. Continue to Add measurements to the list as necessary until complete. h. To move a measurement in the list, select the measurement name and click Move Up or Move Down to relocate the measurement.

4-6

2001-0141 Rev. B

Analyzing AEP/CAEP Tests

Note: A maximum of three measurements may be displayed on the Review Screen Toolbar.” If three measurements are selected, the following message will appear when an attempt to select another item is made: “This measurement can’t be marked as displayed because the maximum number of displayed measurements has been reached.” To remove a measurement from display on the Review Screen Toolbar: a. Either Double-Click on the word Yes in the column labeled Display? for the marker to remove from the toolbar, or highlight the measurement to be changed and select edit. The Measurement window will be displayed. b. Remove the checkmark from the checkbox Measurement appears on Review screen toolbar. Note: If a previously used marker set is edited, all markers placed using that marker set will be changed accordingly. For this reason it is advisable to create new personalized Marker Sets, rather than editing created Marker Sets. The following example illustrates a typical AEP Marker Set.

• Marker labels might include I, II, III, IV and V. • Measurements associated with the marker labels might include Peak Latency for all markers, Peak Amplitudes of peaks I and V and Interpeak intervals between peaks I-III, III-V and/or I-V. 4.

When all required measurements have been entered on the Measurements Tab, click the Reference Data Tab to enter the reference data that have been collected.

5.

Define the Reference Data, if any, that will be applied to waveforms acquired with the Test Set. The use of Reference Data is optional; however, if used, it is advisable to collect reference data for normal hearing subjects, covering a wide range of ages using the test protocols used in the clinic. When reference data has been collected for the GSI Audera system, it can be entered into the Reference Data Tab to be compared to acquired test results using the Latency / Intensity function in the Review screen. Each Marker Set may have multiple sets of Reference Data associated with it.

2001-0141 Rev. B

4-7

GSI Audera

Note: GSI does not take responsibility for the reference data entered and usage of that data by clinicians. Reference data currently in the GSI Audera is for Example only. a. Click on the Reference Data Tab. b. Click the Add button below the Reference group window to display the Reference Group dialog box. Add the name of the reference group, the master units and then the Protocol information. Edit the text in the scroll down window to include as much information on how the reference data was acquired, it should at least show the details listed below. • Version number and date for the reference data. • Number of subjects, their age and sex. • Subjects physical positioning during testing, i.e., upright, reclining, supine, prone, etc. • Subjects state, i.e., awake, relaxed, asleep etc. • Location of the electrode connections on the subject. • Earphones used and their associated acoustic delay. • Stimulus type used. • Stimulus polarity. • Masking noise level, if used. • Repetition rate. • Number of sweeps averaged. • Noise rejection level. • High pass filter cut off frequency, slope of its roll off and its analog equivalent. e.g., 150 Hz, 12 dB/octave, Butterworth. • Low pass filter cut off frequency and type. Note: It is essential that all the above criteria remain constant throughout reference data collection to ensure validity of the reference data collected. c. When the reference data has been named and the above information entered, click Save. The name of the Reference Group and the dB units will appear in the Reference Data Tab. d. Highlight the new name in the display and click Add at the bottom left of the window. This will reveal the Reference Data box (Figure 1).

Figure 1: Reference Data box.

4-8

2001-0141 Rev. B

Analyzing AEP/CAEP Tests

e. Enter the first intensity level for which reference data that was collected. f.

Enter the mean and one standard deviation equivalent value, calculated for that intensity.

g. Click Save. The information appears in the lower section of the Data tab. h. Repeat steps (d) through (f) for all intensities for which reference data was collected. Note: Entering of reference data is optional. Also, the reference data does not have to be complete. For example, there may be reference data for wave V but not for the other waves. There also may only be reference data for one intensity level and none for the other levels. Enter as much or as little information available. i.

To Edit a Marker Set

When all available data has been entered, click Save at the bottom right of the screen. This will place the new Marker Set and Reference Data into the available Marker Sets list in the Test Set Editor. The new Marker Set is now available to include in one or more new Test Sets.

If Marker Sets have not been locked, they can be renamed or deleted. Markers and measurements can also be redefined within the Marker Sets.

Renaming a Marker Set 1.

Highlight the Marker Set Name tab that is to be renamed.

2.

Click Rename.

3.

Enter the new name in the box displayed.

4.

Click Save. The new name will be displayed on the tab.

Deleting a Marker Set 1.

Highlight the Marker Set Name tab that is to be deleted.

2.

Click Delete. A warning will appear to confirm the delete.

3.

Click Yes to delete the Marker Set. Click No to return to Edit Marker dialog box.

Redefining Markers Individual markers may be added or deleted from an existing list of markers, or marker names may be changed.

To Add a Marker Follow steps as shown in Define Markers in previous pages.

To Rename a Marker

2001-0141 Rev. B

1.

Highlight the marker to be edited in marker list.

2.

Click Edit at the bottom of marker table.

3.

Enter the new marker name.

4.

Click Save. This will place the new marker name in the marker list.

5.

Repeat steps 1 through 4 until all markers have been renamed as required.

4-9

GSI Audera

To Delete a marker 1.

Highlight the marker to be deleted from the marker list.

2.

Click Delete at the BOTTOM of the marker table. (DO NOT CLICK DELETE AT THE TOP OF THE MARKER SETS WINDOW AS THIS WILL DELETE THE WHOLE MARKER SET.) A warning will appear to confirm the deletion of the marker.

3.

Click Yes to delete the marker. Click No to return to Edit Marker Set dialog box.

Note: If a previously used Marker Set is changed, all markers placed using that Marker Set will be changed accordingly. When a marker set has been defined, it is advisable to lock the set to avoid changes being made to that Marker Set.

The above chart shows a Latency versus Intensity graph. 1.

After markers have been placed, they can be displayed in this form by clicking Patient > Print AEP Report.

2.

On the AEP Report Selection click Setup next to the Latency intensity check box. Alternatively, select the chart containing the marked waveforms to be displayed on the Latency vs. Intensity graph.

3.

Click the Measurement icon

on the toolbar.

If NO reference data is entered for the Marker Set used, only the latencies from the marked chart will be displayed (the markers will be red or blue depending on the ear displayed). If Reference Data has been entered, the normative range will be displayed as green lines, along with the marked latencies from the chart. Using the controls on the Latency vs. Intensity chart, it is possible to view the marked waveforms compared to reference data. Note: It is recommended to compare waveform latencies with reference data acquired using the same test set parameters and relating to the same age group. Comparing data acquired using different test set parameters may lead to inconsistent findings.

4-10

2001-0141 Rev. B

Analyzing AEP/CAEP Tests

On the Latency vs. Intensity graph, the X represents the stimulus intensity used and is measured in dBnHL. The Y axis represents the time of the latency and is measured in milliseconds (ms). All markers on a chart will be displayed on the Latency vs. Intensity graph. Select a Reference Group from the list on the graph to display reference lines for each of the waves available within the Marker Set used. These reference data points are represented by diamonds connected by green lines. If no Reference Data was entered for any particular marker, only the marked waveforms latencies will appear on the graph. Marker: This display lists all markers available within the Marker Set. The Marker Set is a global parameter defined in the Test Set chosen to acquire the data. Reference Group: Displays the names of all Reference Groups created. Select a Reference Group, which corresponds to the Test Set used and best fits the patient. The reference data for each marker can be displayed (if available) by selecting the required marker. Reference data may not be available for all markers in the Marker Set used. If a marker is selected which has no reference data associated with it, the Latency vs. Intensity graph will display the latencies of the marked waveform only. Left ear marker details are represented by blue symbols and connecting blue lines. Right ear marker details are represented by red symbols and connecting red lines. Note: The selected marker is represented by a different shape to all other markers displayed. The symbol representing the selected waveform marker is defined at the bottom of the window. Protocol – Click this button to display the proforma information entered for the Reference Group selected. This information was defined when the reference data was entered. The proforma information cannot be edited in this window. Deviations – This drop down menu displays a list of Standard deviations available, which can be applied to the Reference Data. A Standard Deviation selected from this list will change the reference data displayed in the window from the default “1.96 Standard Deviation from the Mean” to represent the Standard Deviation selected. Scale Y Axis – This drop down menu displays options available to rescale the Y-axis on the Latency vs. Intensity chart.

• Waveform Maximum is the default setting and represents the time base used to record the chart being displayed.

• Auto scale changes the Y-axis. The Latency vs. Intensity graph is plotted with the maximum Y value being equivalent to the maximum latency marked. All other values within this drop down list change the Y-axis, the value selected being the maximum number available on the Y-axis.

2001-0141 Rev. B

4-11

GSI Audera

Printing an AEP Report 1.

Select Patient > Print AEP Report from the Menu Bar in the review screen. The AEP Report selection is displayed.

2.

This lists all charts recorded in left and right panel. For each chart recorded, it is possible to print the associated chart, measurements and patient details. Deselect items not required for printing.

3.

Check Print Patient History Notes and/or to Print session notes to be included in the AEP report. As default, only the first chart from the left panel and right panel will be selected for printing.

4.

To include other charts in the report. a. Click on the chart that contains any or all of the details to include in the report. b. Check the boxes to select the chart, measurement, or details as required. c. Check the Select All to select all charts, measurements, and details. Deselect items by unchecking the appropriate box.

5.

Click on Preview Report.

Note: Latency vs. Intensity graphs must be configured before printing. This can be achieved in the Review screen or select Setup in the Print AEP Report Selection window. 6.

Click Next page to preview the complete report. Click Print to print the report as outlined in the preview. Click Cancel to return to report contents list if amendments need to be made prior to printing.

Note: The printout will contain all patient details as saved in patient details window, the charts selected with relevant waveform details in tabular form, the examiner, site and date of test.

Printing an AEP Chart

1.

Select the chart from the panel to print by clicking on it in the panel or on the Hierarchical tree.

2.

Select Patient > Print current chart.

3.

A preview of the printout will be displayed.

4.

Select Print then OK to print this report. Select Close to cancel printing and return to the review screen.

Note: The printout will contain the chart selected with appropriate title, the patient's name, examiners name, site and date of test. No measurements of test parameters will be printed.

4-12

2001-0141 Rev. B

5

2001-0141 Rev. B

Appendix

5-1

GSI Audera

Auditory Brainstem Response (ABR) An Auditory Brainstem Response is an electrical potential generated when the ear is stimulated with sound. These potentials are acquired using electrodes placed at defined sites on the scalp. This acquisition is averaged over a specific time period and displayed as a waveform. The peaks and troughs are marked to provide latency and amplitude values; Waves I, III and V are the most significant. ABR morphology varies dependent on the rate and intensity of the stimulus used, but generally the greater the intensity and the slower the rate, the clearer the waveform morphology. Wave V is the most robust waveform; it is present in a normal hearing population at low intensities fast rates. For this reason, when estimating hearing thresholds, faster rates can be used to decrease test time. With neurological evaluation, where all peaks and interpeak values are important, acquisition parameters dictate slower rates with a fixed intensity. The latency values obtained are compared to a normal hearing population to help diagnose specific pathologies.

The Test Setup

The stimulus to elicit an ABR response can be a short duration broad-band stimulus such as a click or the CE-Chirp® or for more frequency specificity, a tone pip or the CE-Chirp octave band stimulus. Surface electrodes are attached as shown in Figure 1. A linker cable is used between the positive inputs.

Jumper between 1+ and 2+

1+ or 2+ High forehead

_

CH

Common Low forehead

GND

+1

Audera Right earlobe 2-

1- Left earlobe

CH

+2

_

TM

Amplifier

> 50 20 - 50 10 - 20 5 - 10 K 2-5 50 20 - 50 10 - 20 5 - 10 K 2-5 Contacting GSI 2-15 Help > View Manual 2-15 Help Menu > About Audera 2-15 Hidden charts or waveforms 2-16 Hide 2-16 Hierarchical Tree 1-4, 2-19 High and Low Pass Filtering 3-11 High pass filters 3-15 How it works 1-5

I Identifying the GSI Audera software version number i-vi Impedance test panel 2-20 Impedance Test window 3-4 Input requirements i-vi Intended operator i-vi Interaual asymmetry 1-6 Invert Chart 2-17 Ipsilateral response 3-5 Items not covered by warranty i-iii

L Late response 1-5 Latencies 1-5 Left and Right Charting Panels 2-18 Left ear marker details 4-11 Light blue 3-5 Limit of warranty i-iii Linear phase versus non linear phase 3-15 Linear phase versus nonlinear phase 3-15 List AEP Test Sets 2-12 List of Standard deviations available 4-11 Lock Test Set 3-10 Loudspeaker 3-9 Low pass filters 3-15

M Manual testing 2-9 Marker 4-11 Marker Set 3-9 Marker Sets 4-9 Markers 4-4

2

Markers on a waveform 4-4 Masking 3-9 Masking Level 3-11 Masking Offset 3-11 Masking type 3-9 Master units 2-13 Measurement appears on printed reports 4-6 Measurement appears on Review screen toolbar 4-6 Measurement Chart 2-18 Measurement Section of the Marker Set 4-6 Measurement Type 4-6 Measurement window 4-6 Menu bar commands 2-5 Moving markers 4-4

N Name the New Marker Set 4-5 Neural units 1-5 nHL adjustment 3-11 No high pass digital filtering 3-15 Nonlinear phase 3-15 Note label i-vii

O Options > AEP Options 2-13, 3-7 Options > Assign Calibration Information 3-9 Options > Default Spread Settings 2-14, 2-15 Options > Edit Marker Set 2-15, 4-5 Output interface i-vi Overlay Ipsi and Contra results for the same level and ear 2-15 Overlay results recorded for the same level and ear 2-15 Overview 1-3

P Patient > Back to Main Screen 2-12 Patient > Edit 2-12 Patient > Print AEP Report 2-12, 4-12 Patient > Print current chart 2-12, 4-12 Patient History 2-18 Pause 2-10 Peak to Peak Interval 4-6 Performing AEP/CAEP Tests 3-1 Performing an AEP test 3-5 Pink limit lines 3-5 Place a text marker 4-5 Previous Results 3-7 Print AEP Report 2-12, 4-12 Print Chart 2-17 Print current chart 2-12, 4-12 Print Patient History Notes 4-12 Print session notes 4-12 Proforma information 4-11 Program Defaults 2-15 Protective classification i-vi Protocol 4-11

2001-0141 Rev. B

Index

R Random test mode 3-9 Read Only 3-10 Red lines 4-11 Red markers 4-10 Red symbols and connecting red lines 4-11 Reference Data box 4-8 Reference Group 4-11 Regulatory standards i-v Reject # 2-10 Rejects % 2-10 Rename 2-17 Rename a Marker 4-9 Rename a Test Set 3-10 Renaming a Marker Set 4-9 Repetition Rate 3-11 Requirements i-vi Reset 2-17 Response 1-8 Review Screen control panel 2-20 Right ear marker details 4-11

S Safety precautions i-viii Safety summary i-vii Safety symbols i-vii Save All 3-13 Save the Test Set as Read Only 3-10 Scale Y Axis 4-11 Sensitivity 3-12 Signal-to-noise ratio 3-15 Smooth 2-17 Software copyright protection i-iv Software warranty i-iv Split acquisition screen left/right 2-13 Spread Settings 2-16 Standard deviations 4-11 Start Auto Test 2-9 Start Auto Test button 2-10 Start automatic testing 2-9 Start manual testing 2-9 Start One Test button 2-10 Start Test 2-9, 2-10 Stimulus Level 3-11 Stimulus Polarity 3-11 Stimulus Relative 3-9, 3-11 Stop Test 2-10 Sub-average size 3-11 Summary of mouse operations available 1-4 Sweeps 2-10 System warranty i-iii

Test Details panel 2-8 Test Impedance 2-9, 2-10, 2-20 Test Item 2-7, 3-11 Test Set 2-7, 3-8 Test set name 3-8 Test state 2-10 Test time 2-10 Tests > Edit AEP Test Sets 3-7 Tests > List AEP Test Sets 2-12 Text Marker 4-5 Toolbar buttons 2-16 Total number of sweeps 2-10 Total Sweeps 3-11 Trademarks i-ii Transducer 1-5

U Use noise checking 3-9 User interface i-vi Using Auto Test 3-7

V View Manual 2-15

W Warning symbol 2-8 Warnings i-vii Warranty i-iii Warranty Period i-iii Waveform Maximum 4-11

X X = stimulus intensity 4-11

Y Y = time of latency 4-11

T T number 2-19 T# copy... 2-16 Terminology 1-4 Test > Edit AEP/CAEP Test Set 2-12 2001-0141 Rev. B

3

GSI Audera

Blank page.

4

2001-0141 Rev. B