IEC 60645-7:2009

IEC 60645-7 ®
Edition 1.0 2009-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electroacoustics – Audiometric equipment –
Part 7: Instruments for the measurement of auditory brainstem responses

Electroacoustique – Equipements audiométriques –
Partie 7: Instruments pour la mesure des réponses du tronc cérébral à une
stimulation auditive
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IEC 60645-7 ®
Edition 1.0 2009-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electroacoustics – Audiometric equipment –
Part 7: Instruments for the measurement of auditory brainstem responses

Electroacoustique – Equipements audiométriques –
Partie 7: Instruments pour la mesure des réponses du tronc cérébral à une
stimulation auditive
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
M
CODE PRIX
ICS 17.140.50 ISBN 978-2-88910-243-3
– 2 – 60645-7 © IEC:2009
CONTENTS
FOREWORD.3
INTRODUCTION.5
1 Scope.6
2 Normative references .6
3 Terms and definitions .6
4 Requirements for specific instruments .7
5 General specifications .8
5.1 Measuring system .8
5.1.1 Units of measurement.8
5.1.2 Measurement range.8
5.1.3 Time resolution.8
5.2 Stimulus system .8
5.2.1 General requirements .8
5.2.2 Stimulus types .8
5.3 Test quality assuring system .8
5.3.1 Recording conditions .8
5.3.2 Response detection.9
5.3.3 Quality estimates.9
5.3.4 Reference values.9
5.4 Presentation of results .9
6 Demonstration of conformity with specifications.9
6.1 General .9
6.2 Signal-to-noise ratio improvement .9
6.3 Maximum permitted expanded uncertainty of measurements U .9
max
7 General requirements .10
7.1 Marking .10
7.2 Instruction manual.10
7.3 Safety requirements .10
7.3.1 General .10
7.3.2 Immunity to power and radiofrequency fields .10
7.4 Warm-up time.10
7.5 Voltage supply variation and environmental conditions .11
7.5.1 Mains operation.11
7.5.2 Battery operation .11
7.5.3 Environmental conditions.11
8 Routine calibration .11
Bibliography.12

Table 1 – Instrumentation requirements .7
Table 2 – Documentation of test conditions, parameters and results .9
Table 3 – Values of U for basic measurements .10
max
60645-7 © IEC:2009 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
_____________
ELECTROACOUSTICS –
AUDIOMETRIC EQUIPMENT –
Part 7: Instruments for the measurement
of auditory brainstem responses

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60645-7 has been prepared by IEC technical committee 29:
Electroacoustics.
The text of this standard is based on the following documents:
FDIS Report on voting
29/674/FDIS 29/682/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 4 – 60645-7 © IEC:2009
The list of all the parts of the IEC 60645 series, under the general title Electroacoustics –
Audiometric equipment, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
60645-7 © IEC:2009 – 5 –
INTRODUCTION
Developments in the field of diagnostic hearing measurement have resulted in a number of
instruments designed to evaluate the auditory evoked potentials of the human hearing system
which can be evoked by acoustic or vibratory signals having different spectral and temporal
characteristics. The practical use of such instruments concerns the measurement of these
electric potentials and their separation from electric signals emerging from other physiological
or artificial sources.
– 6 – 60645-7 © IEC:2009
ELECTROACOUSTICS –
AUDIOMETRIC EQUIPMENT –
Part 7: Instruments for the measurement
of auditory brainstem responses

1 Scope
This part of IEC 60645 applies to instruments designed for the measurement of auditory
evoked potentials from the inner ear, the auditory nerve and the brainstem, evoked by
acoustic and/or vibratory stimuli of short duration. This part of IEC 60645 defines the
characteristics to be specified by the manufacturer, specifies performance requirements for
two types of instrument, screening and diagnostic, and specifies the functions to be provided
on these types.
The purpose of this part of IEC 60645 is to ensure that measurements made under
comparable test conditions with different instruments complying with this standard will be
consistent. This part of IEC 60645 is not intended to restrict development or incorporation of
new features, nor to discourage innovative approaches.
The application of electric stimuli for special purposes is beyond the scope of this standard.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60601-1, Medical electrical equipment – Part 1: General requirements for basic safety
and essential performance
IEC 60645-1:2001, Electroacoustics – Audiological equipment – Part 1: Pure-tone
audiometers
IEC 60645-3:2007, Electroacoustics – Audiometric equipment – Part 3: Test signals of short
duration
ISO 389 (all parts), Acoustics – Reference zero for the calibration of audiometric equipment
ISO/IEC Guide 98-3, Uncertainty of measurement – Part 3: Guide to the expression of
uncertainty in measurement (GUM:1995)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
auditory evoked potentials
AEP
electric potentials which can be evoked by acoustic or vibratory stimulation of the auditory
system and recorded by means of electrodes

60645-7 © IEC:2009 – 7 –
3.2
electric response audiometry
ERA
method for recording the AEPs
3.3
auditory brainstem response
ABR
transient AEPs generated in the inner ear, the auditory nerve and the brainstem after
stimulation of the ear with an acoustic or vibratory force stimulus of short duration
NOTE A method for recording the ABRs is also known as BERA (brainstem electric response audiometry).
3.4
automated auditory brainstem response
AABR
automatic detection of auditory brainstem responses
4 Requirements for specific instruments
Two different types of ERA instrument are specified by the requirements for minimum
mandatory functions (see Table 1). Other functions are not precluded. The two types relate to
their presumed primary application (diagnostic/clinical and screening).
Table 1 – Instrumentation requirements
Type
1 2
Feature Diagnostic/clinical Screening
Stimulus
Stimulus according to IEC 60645-3 x x
Adjustable stimulus level, level control x
Contra-lateral masking facility x
Signal processing
Artefact rejection x x
User adjustable averaging x
Automatic response detection x
Presentation of results
Display of result x
Display of PASS/REFER x
Display of a quality measure x
Documentation
Display, internal/external storage, and export of x
test results/parameters
If a different test signal is used, it shall be described by the manufacturer.
Usually a white noise signal is used for contra-lateral masking.

– 8 – 60645-7 © IEC:2009
5 General specifications
5.1 Measuring system
5.1.1 Units of measurement
SI units or derived SI units shall be used. The units of measurement shall be indicated.
5.1.2 Measurement range
The minimum measurement ranges for AEP shall be from 10 nV to 2 μV for instruments of
Type 1.
5.1.3 Time resolution
The time resolution shall be 0,1 ms or better for instruments of Type 1.
NOTE The minimum time resolution is determined by the sampling rate of the device. The amplitude accuracy
limit is given by the internal noise.
5.2 Stimulus system
5.2.1 General requirements
Specifications for the stimulus system are as given in the relevant parts of Clauses 6, 8 and
10 of IEC 60645-1:2001, and Clause 5 of IEC 60645-3:2007 with the exceptions specified
below.
5.2.2 Stimulus types
5.2.2.1 General
The general properties and temporal characteristics of the stimulus signal are specified in
IEC 60645-3. Other stimulus types shall be specified by the manufacturer, if applicable.
5.2.2.2 Masking signal
The manufacturer shall provide the frequency characteristics and levels of the masking signal.
5.2.2.3 Stimulus levels
For instruments of Type 1, stimulus levels shall cover a hearing level range of at least 30 dB
to 80 dB. For instruments of Type 2, the stimulus level range shall be specified by the
manufacturer.
5.3 Test quality assuring system
5.3.1 Recording conditions
A facility for checking the test conditions shall be provided, for example, by checking the
electrical impedance between the electrodes.
The system shall be able to improve the initial signal-to-noise ratio by at least 30 dB in the
relevant frequency range, for example, by an averaging procedure.
An artefact rejection system shall be provided.

60645-7 © IEC:2009 – 9 –
5.3.2 Response detection
If an algorithm is used for automatic detection (mandatory for Type 2 instruments), its
statistical significance shall be validated by the manufacturer.
5.3.3 Quality estimates
The efficiency of the method used for estimation of residual noise shall be documented by the
manufacturer.
5.3.4 Reference values
Reference hearing threshold values are given in the ISO 389 series. If other reference values
are used, these data shall be validated and documented by the manufacturer.
5.4 Presentation of results
All relevant information concerning stimulus, recording conditions and results according to
Table 2 shall be stored and be available on demand. The information shall be presented on
display of the instrument and/or as paper printout.
Table 2 – Documentation of test conditions, parameters and results
Type
1 2
Diagnostic/clinical Screening
Stimulus level x x
Contra-lateral masking x
Test conditions x
Number of rejected and accepted records x
Artefact rejection limit x
Graphic display of full result x
Display of PASS/REFER x
Test quality x
For example, artefacts during test, EEG level, electrode impedance, etc.

6 Demonstration of conformity with specifications
6.1 General
The following procedures shall be used for ensuring that an instrument meets the
specifications given in this part of IEC 60645.
6.2 Signal-to-noise ratio improvement
The improvement of the signal-to-noise ratio by at least 30 dB in the relevant frequency range
shall be verified by a suitable procedure as specified by the manufacturer.
6.3 Maximum permitted expanded uncertainty of measurements U
max
Table 3 specifies the maximum permitted expanded uncertainty U calculated with a
max
coverage factor of k = 2 to give a level of confidence of approximately 95 %, associated with
the measurements undertaken in this part of IEC 60645, according to ISO/IEC Guide 98-3.
One set of values for U is given for basic type approval measurements.
max
– 10 – 60645-7 © IEC:2009
The expanded uncertainties of measurements given in Table 3 are the maximum permitted for
demonstration of conformance to the requirements of this standard. If the actual expanded
uncertainty of a measurement performed by the test laboratory exceeds the maximum
permitted value in Table 3, the measurement shall not be used to demonstrate conformance
to the requirements of this part of IEC 60645.
Table 3 – Values of U for basic measurements
max
Measured Relevant Basic
quantity subclause number U (k = 2)
max
Measurement range 5.1.2 3 nV
Time resolution 5.1.3 0,03 ms
Stimulus levels 5.2.2.3 1,0 dB
Signal-to-noise ratio 5.3.1 1,0 dB
Temperature 7.5.3
0,5 °C
Relative humidity 7.5.3 5 %
Ambient pressure 7.5.3 0,1 kPa

7 General requirements
7.1 Marking
The instrument shall be marked according to the requirements of 15.1 of IEC 60645-1:2001.
7.2 Instruction manual
An instruction manual shall be supplied with each instrument. In this manual the manufacturer
shall specify all characteristics as required by this standard and by the relevant statements of
15.2 of IEC 60645-1:2001, as well as the efficiency and supporting evidence for the validation
of the screening algorithm, e.g. the PASS/REFER criteria.
7.3 Safety requirements
7.3.1 General
Instruments shall conform to IEC safety requirements specified in IEC 60601-1.
7.3.2 Immunity to power and radiofrequency fields
During, and as a result of, any EMC immunity testing under the EMC test conditions, the
unwanted sound from any transducer shall not exceed a hearing level of 80 dB. Subclause
13.3 of IEC 60645-1 gives methods for showing conformity.
7.4 Warm-up time
The maximum warm-up time shall be specified by the manufacturer and shall not exceed
10 min when the unit has been stored at room temperature. The performance requirements of
this standard shall be met after the started warm-up time has elapsed and after any setting-up
adjustments have been carried out in the manner prescribed by the manufacturer.

60645-7 © IEC:2009 – 11 –
7.5 Voltage supply variation and environmental conditions
7.5.1 Mains operation
The specifications shall be met when any long-term deviation in any supply voltage or mains
frequ
...