SIST EN IEC 60268-22:2021
(Main)Sound system equipment - Part 22: Electrical and mechanical measurements on transducers (IEC 60268-22:2020)
Sound system equipment - Part 22: Electrical and mechanical measurements on transducers (IEC 60268-22:2020)
IEC 60268-22:2020 applies to transducers converting an electrical input signal into a mechanical or acoustical output signal. However, if the electrical input terminals and the surface of the radiator are accessible, this document can also apply to passive and active sound systems such as loudspeakers, headphones, TV-sets, multi-media devices, personal portable audio devices, automotive sound systems and professional equipment. This document describes only electrical and mechanical measurements that help assess the transfer behaviour of the device under test (DUT). This includes operating the DUT in both the small- and large-signal domains. The influence of the target application's acoustical boundary conditions (e.g. car interior) can also be considered in the physical evaluation of the sound system. Perception and cognitive evaluations of the reproduced sound and the impact of perceived sound quality are outside the scope of this document.
Elektroakustische Geräte - Teil 22: Elektrische und mechanische Messungen an Wandlern (IEC 60268-22:2020)
Équipements pour systèmes électroacoustiques - Partie 22: Mesurages électriques et mécaniques sur transducteurs (IEC 60268-22:2020)
L'IEC 60268-22:2020 s'applique aux transducteurs qui convertissent un signal d'entrée électrique en signal de sortie mécanique ou acoustique. Toutefois, si les bornes d'entrée électriques et la surface du radiateur sont accessibles, le présent document peut également s'appliquer aux systèmes électroacoustiques passifs et actifs tels que les haut parleurs, les casques d'écoute, les téléviseurs, les appareils multimédias, les appareils audio personnels portables, les systèmes électroacoustiques pour automobile et les équipements professionnels. Le présent document ne décrit que les mesurages électriques et mécaniques qui aident à évaluer le comportement de transfert de l'appareil soumis à l'essai (DUT). Cela comprend le fonctionnement du DUT dans les domaines des signaux faibles et des signaux forts. L'influence des conditions de limite acoustique de l'application visée (par exemple, habitacle d'un véhicule) peut également être prise en considération dans l'évaluation physique du système électroacoustique. La perception et les évaluations cognitives du son reproduit et l'impact de la qualité acoustique perçue n'entrent pas dans le domaine d'application du présent document.
Oprema zvokovnega sistema - 22. del: Električne in mehanske meritve na pretvornikih (IEC 60268-22: 2020)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-julij-2021
Oprema zvokovnega sistema - 22. del: Električne in mehanske meritve na
pretvornikih (IEC 60268-22: 2020)
Sound system equipment - Part 22: Electrical and mechanical measurements on
transducers (IEC 60268-22:2020)
Elektroakustische Geräte - Teil 22: Elektrische und mechanische Messungen an
Wandlern (IEC 60268-22:2020)
Équipements pour systèmes électroacoustiques - Partie 22: Mesurages électriques et
mécaniques sur transducteurs (IEC 60268-22:2020)
Ta slovenski standard je istoveten z: EN IEC 60268-22:2020
ICS:
33.160.30 Avdio sistemi Audio systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD EN IEC 60268-22
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2020
ICS 33.160.01
English Version
Sound system equipment - Part 22: Electrical and mechanical
measurements on transducers
(IEC 60268-22:2020)
Équipements pour systèmes électroacoustiques - Partie 22: Elektroakustische Geräte - Teil 22: Elektrische und
Mesurages électriques et mécaniques sur transducteurs mechanische Messungen an Wandlern
(IEC 60268-22:2020) (IEC 60268-22:2020)
This European Standard was approved by CENELEC on 2020-10-29. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 60268-22:2020 E
European foreword
The text of document 100/3311/CDV, future edition 1 of IEC 60268-22, prepared by IEC/TC 100
"Audio, video and multimedia systems and equipment" was submitted to the IEC-CENELEC parallel
vote and approved by CENELEC as EN IEC 60268-22:2020.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2021-07-29
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2023-10-29
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Endorsement notice
The text of the International Standard IEC 60268-22:2020 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following note has to be added for the standard indicated:
IEC 60068-2 (series) NOTE Harmonized as EN IEC 60068-2 (series)
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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.
NOTE 1 Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60263 1982 Scales and sizes for plotting frequency - -
characteristics and polar diagrams
IEC 60268-1 1985 Sound system equipment. Part 1: General HD 483.1 S2 1989
IEC 60268-2 1987 Sound system equipment. Part 2: Explanation HD 483.2 S2 1993
of general terms and calculation methods
IEC 60268-11 1987 Sound system equipment. Part 11: Application HD 483.11 S3 1993
of connectors for the interconnection of sound
system components
IEC 60268-12 1987 Sound system equipment. Part 12: Application EN 60268-12 1995
of connectors for broadcast and similar use
IEC 60268-21 2018 Sound system equipment - Part 21: Acoustical EN IEC 60268-21 2018
(output-based) measurements
IEC 62458 2010 Sound system equipment - Electroacoustical EN 62458 2011
transducers - Measurement of large signal
parameters
IEC 62459 2010 Sound system equipment - Electroacoustical EN 62459 2011
transducers - Measurement of suspension
parts
ISO 3 1973 Preferred numbers - Series of preferred - -
numbers
ISO/IEC GUM 1995 Guide to the expression of uncertainty in - -
measurement (GUM)
IEC 60268-22 ®
Edition 1.0 2020-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Sound system equipment –
Part 22: Electrical and mechanical measurements on transducers
Équipements pour systèmes électroacoustiques –
Partie 22: Mesurages électriques et mécaniques sur transducteurs
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.160.01 ISBN 978-2-8322-8815-3
– 2 – IEC 60268-22:2020 © IEC 2020
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms, definitions and abbreviated terms . 9
3.1 Terms and definitions . 9
3.2 Abbreviated terms . 9
4 Type description . 9
5 Marking of terminals and controls . 9
6 Physical characteristics . 9
6.1 Dimensions . 9
6.2 Mass . 10
6.3 Connectors and cable assemblies . 10
7 Conditions . 10
7.1 Rated conditions . 10
7.2 Climatic conditions . 10
7.3 Standard measuring conditions . 10
8 Test signals . 11
8.1 General . 11
8.2 Small-signal condition . 11
9 Acoustical environment . 11
9.1 General . 11
9.2 Free-field conditions . 11
9.3 Half-space, free-field conditions . 12
9.4 Free-air condition . 12
9.5 Target application conditions . 12
9.6 Vacuum condition . 12
9.7 Plane-wave tube condition . 12
9.8 Non-acoustical measurement condition . 12
10 Positioning of the radiator . 13
10.1 Rated geometrical conditions . 13
10.2 Target application condition . 14
11 Measurement equipment and test results . 14
12 Accuracy of the mechanical and electrical measurement . 14
13 Mounting of the DUT . 14
13.1 Mounting and acoustic loading of drive units . 14
13.2 Mounting and acoustic loading of an electro-acoustic system . 15
13.3 Requirements for laser vibrometry . 15
14 Preconditioning . 15
15 Rated ambient conditions . 15
15.1 Temperature ranges . 15
15.2 Humidity ranges . 15
16 Electrical signals at transducer terminals . 16
16.1 Rated maximum input value . 16
17 Electrical input power . 17
IEC 60268-22:2020 © IEC 2020 – 3 –
17.1 Real input power . 17
17.2 Power dissipated in DC resistance . 17
17.3 Power dissipated in rated impedance . 18
17.4 Rated maximum input power . 18
18 Electrical input impedance . 18
18.1 Complex electrical impedance . 18
18.2 Rated Impedance: characteristic to be specified . 19
19 Vibration of the radiator surface . 19
19.1 General . 19
19.2 Displacement of a surface point r . 19
r
19.3 Reference displacement. 20
19.4 Peak and bottom displacement . 21
19.5 DC displacement . 21
19.6 Displacement transfer function . 22
19.7 Accumulated acceleration level . 22
20 Small-signal lumped parameters . 23
20.1 General . 23
20.2 Electrical parameters . 24
20.3 Relative lumped parameters . 25
20.4 Lumped mechanical parameters. 28
20.5 Pure lumped mechanical parameters . 31
20.6 Compliance versus frequency . 31
20.7 Distributed mechanical parameters . 32
20.8 Lumped acoustical parameters . 36
21 Electro-acoustical efficiency . 40
21.1 Reference efficiency . 40
21.2 Passband efficiency . 41
22 Sensitivity . 41
22.1 Reference sensitivity . 41
22.2 Passband sensitivity . 42
23 Large-signal characteristics . 42
23.1 Electrical and mechanical nonlinearities . 42
23.2 Other loudspeaker nonlinearities . 43
23.3 Asymmetry of the nonlinearity . 43
23.4 Offset from reference rest position, x . 45
off
23.5 Maximum reference displacement . 46
24 Thermal characteristics . 48
24.1 General . 48
24.2 Increase in voice coil temperature . 48
24.3 Effective thermal resistance . 49
24.4 Thermal parameters . 49
24.5 Thermal time constant of the voice coil . 50
24.6 Thermal bypass factor. 50
25 Time variance of the loudspeaker characteristics . 50
25.1 Fatigue and load induced aging . 50
26 Measurement uncertainty . 52
Annex A (informative) Practical application guide . 54
– 4 – IEC 60268-22:2020 © IEC 2020
Bibliography . 55
Figure 1 – Rated conditions used to describe the geometry and position of the radiator
in the coordinate system . 13
Figure 2 – Equivalent electrical network representing the electrical input impedance
using the LR2 model for the lossy inductance of an electro-dynamical transducer . 23
Figure 3 – Analogous lumped parameter network representing the electrical,
mechanical and acoustical elements at low frequencies . 27
Figure 4 – Asymmetrical mass distribution function D (y,z ) in the mechanical system
M 0
of a microspeaker that shifts the centre of gravity away from the pivot point . 34
Figure 5 – Equivalent electrical network of a transducer operated in a baffle
represented by pure mechanical elements and additional acoustical elements . 38
Figure 6 – Equivalent electrical network representing the electrical input impedance of
a vented loudspeaker system . 39
Figure 7 – Nonlinear force factor characteristic of an electro-dynamical transducer . 45
Table A.1 – Important characteristics and their application . 54
IEC 60268-22:2020 © IEC 2020 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SOUND SYSTEM EQUIPMENT –
Part 22: Electrical and mechanical measurements on transducers
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
misinterpretation by any end user.
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 itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
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 60628-22 has been prepared by technical area 20: Analogue and
digital audio, of IEC technical committee 100: Audio, video and multimedia systems and
equipment.
The text of this International Standard is based on the following documents:
CDV Report on voting
100/3311/CDV 100/3424/RVC
Full information on the voting for the approval of this International Standard can be found in the
report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 60268 series, published under the general title Sound system
equipment, can be found on the IEC website.
– 6 – IEC 60268-22:2020 © IEC 2020
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.
IEC 60268-22:2020 © IEC 2020 – 7 –
INTRODUCTION
Measurements of the electrical and mechanical state variables have become increasingly
important for the following reasons:
• Maximum sound pressure output is limited by voice coil heating and transducer
nonlinearities. The large signal behaviour of loudspeakers can be described by nonlinear
and thermal models using lumped parameters. These physical characteristics are important
for transducer design and system integration.
• Mechanical vibration of the diaphragm determines the radiated sound. The modal vibration
of the radiator's surface can be predicted by numerical simulations (FEA) and directly
measured by laser vibrometry. This data represents important transducer characteristics
that can be used to design the desired directivity into the system's acoustical output.
• DSP plays an important role in active systems. Digital pre-processing of the audio stream
requires reliable transducer property information to protect the transducer against thermal
and mechanical overload and to actively compensate for linear and nonlinear distortion
generated in the output signal.
– 8 – IEC 60268-22:2020 © IEC 2020
SOUND SYSTEM EQUIPMENT –
Part 22: Electrical and mechanical measurements on transducers
1 Scope
This part of IEC 60268 applies to transducers converting an electrical input signal into a
mechanical or acoustical output signal. However, if the electrical input terminals and the surface
of the radiator are accessible, this document can also apply to passive and active sound
systems such as loudspeakers, headphones, TV-sets, multi-media devices, personal portable
audio devices, automotive sound systems and professional equipment. This document
describes only electrical and mechanical measurements that help assess the transfer behaviour
of the device under test (DUT). This includes operating the DUT in both the small- and large-
signal domains. The influence of the target application's acoustical boundary conditions (e.g.
car interior) can also be considered in the physical evaluation of the sound system. Perception
and cognitive evaluations of the reproduced sound and the impact of perceived sound quality
are outside the scope of this document.
NOTE This document does not apply to microphones and other sensors. Implementation of this document does not
require access to the sound pressures generated in the near or far fields of the radiator. Directivity and other
characteristics describing the electro-acoustical transfer properties are described in IEC 60268-21, which covers
acoustical measurements.The practical application of the measurements for research and development (R&D), end-
of-line testing (QC) and evaluation in the final target application (TA) is discussed in Annex A.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 60263:1982, Scales and sizes for plotting frequency characteristics and polar diagrams
IEC 60268-1:1985, Sound system equipment – Part 1: General
IEC 60268-2:1987, Sound system equipment – Part 2: Explanation of general terms and
calculation methods
IEC 60268-11:1987, Sound system equipment – Part 11: Application of connectors for the
interconnection of sound system components
IEC 60268-12:1987, Sound system equipment – Part 12: Application of connectors for
broadcast and similar use
IEC 60268-12:1987/AMD1:1991
IEC 60268-21:2018, Sound system equipment – Part 21: Acoustical (output-based)
measurements
IEC 62458:2010, Sound system equipment – Electroacoustical transducers – Measurement of
large signal parameters
IEC 62459:2010, Sound system equipment – Electroacoustical transducers – Measurement of
suspension parts
IEC 60268-22:2020 © IEC 2020 – 9 –
ISO 3:1973, Preferred numbers – Series of preferred numbers
ISO/IEC GUM:1995, Guide to the expression of uncertainty in measurement (GUM)
3 Terms, definitions and abbreviated terms
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1 Terms and definitions
3.1.1
linear behaviour
behaviour of the DUT at small amplitudes where the relationship between input and output
signal can be modelled by a linear system and described by a linear transfer function
3.1.2
reference unit
DUT having measured properties representative of units in the sample lot passing the end-of-
line test
3.2 Abbreviated terms
DUT device under test
SPL sound pressure level
FEA finite element analysis
FT Fourier transform
4 Type description
The type description shall be provided by the manufacturer, including the following information:
• transduction principle (e.g. electro-dynamical, capacitive, electro-magnetic transducer);
• system description including operation principle (e.g. the number of the transducers used in
the loudspeaker system;
• acoustical loading (e.g. horn loading and enclosure types, such as bass reflex, column, line
array, .);
• power amplification (e.g. maximum output power, class type, minimum load impedance, …);
• DSP processing (e.g. equalizer, active protection), if any.
5 Marking of terminals and controls
The terminals and controls shall be marked in accordance with IEC 60268-1 and IEC 60268-2.
6 Physical characteristics
6.1 Dimensions
The outer dimensions of the DUT shall be specified.
– 10 – IEC 60268-22:2020 © IEC 2020
6.2 Mass
The total mass of the DUT when ready for use shall be specified.
6.3 Connectors and cable assemblies
Cable assemblies and connectors shall be in accordance with IEC 60268-11 and IEC 60268-12.
NOTE In some circumstances, the connectors that are currently standardized are unsuitable and the use of other
types is unavoidable.
7 Conditions
7.1 Rated conditions
Standard measuring conditions are defined in 7.3. To obtain the actual conditions for the
measurement, some values (known as "rated conditions") shall be taken from the
manufacturer's specification.
These rated conditions are not subject to measurement, but they constitute the basis for
performing the measurements to determine the other characteristics.
The following rated conditions are of this type and shall be stated by the manufacturer:
• rated maximum input voltage (or the rated maximum sound pressure level);
• rated maximum input power;
• evaluation point of the reference displacement;
• rated frequency range;
• rated impedance;
• rated climate conditions.
7.2 Climatic conditions
7.2.1 Conditions for normal testing
IEC 60268-1 states that tests should be carried out in the following environment in order to
prevent the influence of temperature and humidity that can affect the properties of the drive unit
suspensions:
• ambient temperature T : 15 °C to 35 °C;
norm
• relative humidity: 25 % to 75 %;
• air pressure: 86 kPa to 106 kPa.
7.2.2 Conditions for climatic testing
The manufacturer shall specify the ambient temperature T and other climatic conditions under
A
which the DUT is operated during thermal testing in accordance with 25.1.4.
7.3 Standard measuring conditions
The DUT shall be understood to be under standard measuring conditions if all of the following
conditions are specified and implemented:
a) the DUT to be measured is mounted in accordance with Clause 13;
b) the acoustical environment is specified and selected from those given in Clause 9;
IEC 60268-22:2020 © IEC 2020 – 11 –
NOTE The environment (e.g. car interior) might influence the acoustical load and the mechanical state of the
transducer. If the amplitude of the stimulus used in the measurements is adjusted based on the rated maximum
(output) sound pressure level L in accordance with IEC 60268-21, the acoustical environment is considered.
MAX
c) unwanted electrical, mechanical or acoustical signals (e.g. noise) generated by other
sources shall be kept at the lowest levels possible because their presence can obscure low-
level signals. Data related to signals that are less than 20 dB above the noise level in the
frequency band being considered shall be discarded or marked as corrupted by noise;
d) the DUT is acclimatized to the normal climatic conditions (normal ambient temperature
T = T ) in accordance with 7.2.1;
A norm
e) additional cooling periods are required between successive tests if the amplitude
compression C(f) > 0,5 dB is in accordance with IEC 60268-21;
f) the DUT is supplied with a test signal with specified properties (spectrum, duration, etc.) in
~
accordance with Clause 8 at a specified RMS input value for the rated frequency range
u
in accordance with Clause 16;
g) attenuators, equalizers, dynamics and any other active control elements shall be set to their
"normal" position as stated by the manufacturer. If other positions are chosen, for example,
those providing a maximally flat frequency response or minimum attenuation, they shall be
specified;
h) measuring equipment suitable for determining the wanted characteristics is connected in
accordance with Clause 11.
8 Test signals
8.1 General
Some measurements can be performed by using any audio signal s(t) as an input signal
(stimulus) applied to the electro-acoustical device under test (DUT) while other measurement
techniques use test signals as specified in IEC 60268-21.
8.2 Small-signal condition
The device under test shall be excited by a stimulus s(t) generating the voltage ut = αu s t
( ) ( )
max
at the terminals scaled by the maximum input value u and scaling factor α. The rated
max
maximum input value u shall be specified by the manufacturer of the DUT in accordance
max
with 16.1. The scaling factor α shall be less than 0,1 to ensure negligible heating of the voice
coil in electro-dynamic transducers (ΔT < 5 K) and linear behaviour of the device under test.
v
The nonlinear distortion components measured through the excitation of a single tone, two tone
or multitone stimulus shall be 40 dB below the fundamental signal components.
9 Acoustical environment
9.1 General
Electrical and mechanical measurements shall be made under one of the conditions in 9.2 to
9.8. The acoustical environment used for testing shall be stated.
9.2 Free-field conditions
An environment, which fullfills free-field conditions in full space in accordance with
IEC 60268‑21, can be used for electrical and mechanical measurements. If the environment
(e.g. anechoic room at low frequencies) does not fulfil these free-field conditions over the entire
frequency range of the measurement, the manufacturer shall state the valid frequency range.
– 12 – IEC 60268-22:2020 © IEC 2020
9.3 Half-space, free-field conditions
An environment, which fulfills free field condition in a half space in accordance with
IEC 60268‑21 can be used for electrical and mechanical measurements. These conditions shall
be satisfactorily met with a reflecting plane of sufficient size.
If the environment (e.g. half space anechoic room at low frequencies) does not fulfil these half-
space free field conditions over the entire frequency range of the measurement, the
manufacturer shall state the valid frequency range.
9.4 Free-air condition
Acoustical conditions that approach free-field condition over the frequency range of interest
shall be used. Other environments shall be considered satisfactory when the reflected sound
components are sufficiently suppressed to ensure an accuracy of ±5 % in the measured
amplitude and phase values of the electrical input impedance curve at the specified frequency.
If the environment (e.g. a small measurement room at low frequencies) does not fulfil these
conditions over the entire frequency range of the measurement, the manufacturer shall state
the valid frequency range.
NOTE The free-air condition is usually applied to transducers operated without enclosure but firmly clamped by a
fixture to measure the electrical and mechanical state of the transducer.
9.5 Target application conditions
Acoustical conditions that correspond with the final target application of the device under test
(e.g. sound system mounted in a car, horn compression driver mounted on a horn).
9.6 Vacuum condition
9.6.1 General
Acoustical conditions which approach those of no air.
9.6.2 Method of measurement
Transducer electrical impedance are measured and stored. The transducer is then placed in a
vacuum chamber and the evacuation is started. Note if any outgassing from glues or plastic
materials occurs – the vacuum will be drawn down slower than expected. Transducer electrical
impedance is then measured and stored. The vacuum is then released to restore normal
atmospheric pressure. The transducer electrical impedance is measured and stored, and the
data is then compared to the initial stored measurement to see if any changes have occurred
due to material(s) changes from outgassing.
9.7 Plane-wave tube condition
A plane-wave tube is intended to provide an approximately constant acoustical impedance with
a value ρ c identical to the specific impedance of air.
o
NOTE Plane-wave tubes are used to provide a standard load for the testing of compression drivers, see AES-1id-
2012 [1] .
9.8 Non-acoustical measurement condition
Electrical and mechanical measurements can be performed in a room of sufficient size
(typically > 8 m ). The size of the room depends on the space required around the DUT to avoid
any additional acoustical loading of the DUT and to ensure stable climate conditions during the
test.
___________
Numbers in square brackets refer to the Bibliography.
IEC 60268-22:2020 © IEC 2020 – 13 –
10 Positioning of the radiator
10.1 Rated geometrical conditions
10.1.1 General
The position and orientation of the diaphragm, cone or other kind of radiator used in the DUT
shall be stated using the radiator's reference point r , the normal vector n and the orientation
r,ref r
vector o as illustrated in Figure 1.
r
Figure 1 – Rated conditions used to describe the geometry and position of the radiator
in the coordinate system
10.1.2 Reference plane and normal vector
The reference plane with the normal vector n shall be used to define the reference axis and
r
the reference point r .
r,ref
NOTE For symmetrical structures, the reference plane is usually parallel to the radiating surface at the rest position
of the radiator. For asymmetrical structures, the reference plane is better indicated by means of a diagram.
10.1.3 Reference point
The reference point r shall be a point on the radiator's surface intersecting the reference
r,ref
plane. The position of the reference point r shall be specified by the manufacturer.
r,ref
NOTE For symmetrical structures, reference point r is usually the point of axial symmetry of the radiator within
r,ref
the reference plane. For asymmetrical structures, the reference point is better indicated by means of a diagram.
10.1.4 Orientation vector
The orientation vector o defines the orientation of the radiator within the reference plane and
r
the direction of the azimuthal angle φ in spherical coordinates.
NOTE The preferred orientation vector places the reference point r at the origin O of the coordinate system,
r
pointing the normal vector n of the reference plane into the z-direction while the polar angle θ = 0 turns the audio
r
system in such a way that the orientation vector o (e.g. top of the enclosure) points into the x-direction.
r
– 14 – IEC 60268-22:2020 © IEC 2020
10.2 Target application condition
The position and orientation of the radiator with respect to the target environment (car interior,
pinna adaptor with ear canal simulator, etc.) shall be described by means of a diagram
appended to the measurement results.
11 Measurement equipment and test results
Graphical results shall conform to the preferred aspect ratios in IEC 60263.
Frequency data, if provided in addition to the graphs, shall be at the ISO R40 preferred
frequencies, unless otherwise stated.
The measurement of the voltage at the terminals of the device under test shall be made using
sensing wires in addition to the two driving wires (four wire technique) so that negligible current
is generated in the sensing wire.
NOTE The resistance of the cables and current sensors (e.g. measurement resistor) can affect the accuracy of the
impedance measurement and the input voltage at the device under test.
12 Accuracy of the mechanical and electrical measurement
Probable error sources in both the instrumentation and measuring environment shall be
identified, quantified and their contribution shall be specified. Uncertainties in the position and
calibration of the sensors shall be stated. This information shall be included with the test report.
13 Mounting of the DUT
13.1 Mounting and acoustic loading of drive units
The performance of the drive unit (transducer) is determined by the properties of the unit itself
and its acoustic loading. The acoustic loading depends upon the mounting arrangement, which
shall be clearly described in the presentation of the results.
One of the following types of mounting shall be used:
a) half-space free-field condition generated by mounting the transducer flush with a plane
reflecting surface according conditions defined in 9.3. Half-space loading for transducers is
preferred;
b) a standard baffle with a plane front surface that is acoustically reflecting, as specified in
IEC 60268-21;
c) a standard measuring enclosure (type A or type B) as specified in IEC 60268-21, generating
a defined rear air volume and radiation condition at the front of the transducer;
d) a loudspeaker driver comparison chamber as specified in AES X223 [2];
e) a test cabinet generating a defined air load and radiation condition at the front of the
transducer for end-of-line testing and relative measurements;
NOTE An additional chamber located at the rear side of the transducer can be used to provide additional noise
isolation or it could be used to consider the influence of the air volume of a sealed box in the target application.
f) a defined horn, coupler or other kind of wave guide that couples the radiating surface of the
transducer in the target application to the surrounding sound field;
g) a plane wave tube as specified in 9.7;
h) the transducer is operated in free air and is firmly clamped by a fixture to reduce the
vibration of the frame and magnet;
IEC
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