National foreword

This British Standard is the UK implementation of EN IEC 60268‑21:2018. It is identical to IEC 60268‑21:2018.

The UK participation in its preparation was entrusted to Technical Committee EPL/100, Audio, video and multimedia systems and equipment.

A list of organizations represented on this committee can be obtained on request to its secretary.

This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity from legal obligations.

This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 January 2019.

FOREWORD

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.
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.
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.
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.
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.
All users should ensure that they have the latest edition of this publication.
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.
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.
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 60268‑21 has been prepared by IEC technical committee 100: Audio, video and multimedia systems and equipment.

The text of this standard is based on the following documents:

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 60628, published under the general title Sound system equipment, can be found on the IEC website.

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.

A bilingual version of this publication may be issued at a later date.

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.

INTRODUCTION

Loudspeakers, headphones and other actuators have become more versatile and, as a result, new measurement techniques are required to evaluate these systems. The following is a list of examples where new measurement techniques are required:

Limited access to the electrical terminals of the transducer
The higher integration of electrical, acoustical and mechanical elements limit the access to the electrical terminals of the transducer.

Analogue or digital audio input signals
Audio inputs can accept analogue or digital signals in various formats.

Latency and other kinds of distortion associated with digital signal processing
Digital signal processing is used to correct the transfer behaviour of the passive system and to generate a desired sound output and as a result, latency and other kinds of distortion not found in analogue equipment can be generated.

Excessive equalization
Excessive equalization can force the transducer to operate in the large signal domain causing thermal and nonlinear effects.

Active protection
Active protection attenuates the input signal to prevent a mechanical and thermal overload of the transducer and other components.

Other transducer principles
Although most loudspeaker systems use a moving coil in an electro-dynamical transducer, there is a need to expand the application to electro-static, electro-magnetic or any other transduction principles.

Other mechanical and acoustical elements
To improve sound radiation, vented enclosures, sealed enclosures, passive radiators, horns, wave guides, flat panels, and other mechanical and acoustical elements are implemented.

Impulsive distortions
Defects in manufacturing (e.g. voice coil rubbing) or operating under overload conditions can create impulsive distortions, which have a high impact on perceived sound quality but cannot be detected by conventional measurements (e.g. total harmonic distortion).

Directional characteristics and complex near field properties
The comprehensive evaluation of professional equipment, including directional characteristics, can be realized by considering the complex near-field properties as a supplement to the existing far-field measurement techniques. In addition, devices intended for use in the near field, such as hand-held personal audio devices (e.g. laptops, tablets, smart phones) and other portable sound systems, need to be evaluated in a manner appropriate to their intended use.

This European Standard was approved by CENELEC on 2018-12-12. 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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

European foreword

The text of document 100/2957/CDV, future edition 1 of IEC 60268‑21, 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 60268‑21:2018.

The following dates are fixed:

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 60268‑21:2018 was approved by CENELEC as a European Standard without any modification.

In the official version, for Bibliography, the following notes have to be added for the standards indicated:

1 Scope

This part of IEC 60268 specifies an acoustical measurement method that applies to electro-acoustical transducers and passive and active sound systems, such as loudspeakers, TV-sets, multi-media devices, personal portable audio devices, automotive sound systems and professional equipment. The device under test (DUT) can be comprised of electrical components performing analogue and digital signal processing prior to the passive actuators performing a transduction of the electrical input into an acoustical output signal. This document describes only physical measurements that assess the transfer behaviour of the DUT between an arbitrary analogue or digital input signal and the acoustical output at any point in the near and far field of the system. This includes operating the DUT in both the small and large signal domains. The influence of the acoustical boundary conditions of the target application (e.g. car interior) can also be considered in the physical evaluation of the sound system. This document does not assess the perception and cognitive evaluation of the reproduced sound and the impact of perceived sound quality.

NOTE Some measurement methods defined in this document can be applied to headphones, headsets, earphones and earsets in accordance with [1] 1. This document does not apply to microphones and other sensors. This document does not require access to the state variables (voltage, current) at the electrical terminals of the transducer. Sensitivity, electric input power and other characteristics based on the electrical impedance will be described in a separate future standard document, IEC 60268‑22, dedicated to electrical and mechanical measurements.

2 Normative references

3 Terms, definitions and abbreviated terms

3.1 Terms and definitions

3.2 Abbreviated terms

4 Type description

5 Physical characteristics

5.1 Marking of terminals and controls

5.2 Dimensions

5.3 Mass

5.4 Connectors and cable assemblies

6 Design data

7 Conditions

7.1 Rated conditions

7.2 Climatic conditions

7.3 Normal measuring conditions

8 Test signals

8.1 General

8.2 Sinusoidal chirp

8.3 Steady-state single-tone signal

8.4 Steady-state two-tone signal

8.5 Sparse multi-tone complex

8.6 Broadband noise signal

8.7 Narrow-band noise signal

8.8 Hann-burst signal

8.9 Impulsive signal

9 Acoustical environment

9.1 General

9.2 Free-field conditions

9.3 Half-space, free-field conditions

9.4 Simulated free-field conditions

9.5 Half-space simulated free-field conditions

9.6 Diffuse sound field conditions

9.7 Target application conditions

10 Positioning of the DUT

10.1 Rated geometrical conditions

10.2 Measuring distance between DUT and microphone

11 Measurement equipment and test results

12 Accuracy of the acoustical measurement

12.1 General

12.2 Measurement uncertainty

13 Mounting of the DUT

13.1 Mounting and acoustic loading of drive units

13.2 Mounting and acoustic loading of an electro-acoustic system

14 Preconditioning

15 Rated ambient conditions

15.1 Temperature ranges

15.2 Humidity ranges

16 Rated frequency range

17 Input signal

17.1 Rated maximum input value

17.2 Maximum input level

18 Sound-pressure output

18.1 Rated maximum sound pressure

18.2 Rated maximum sound-pressure level

18.3 Short term maximum sound pressure level

18.4 Long term maximum sound pressure level

18.5 Sound pressure in a stated frequency band

18.6 Sound-pressure level in a stated frequency band

18.7 Mean sound-pressure in a stated frequency range

18.7.1 Condition to be specified

18.7.2 Method of measurement

18.8 Mean sound-pressure level in a stated frequency range

19 Frequency response of the fundamental component

19.1 Transfer function

19.2 SPL frequency response

19.3 Time-varying amplitude compression of the fundamental component

19.4 Amplitude compression at maximum input

19.5 Corrections based on a free-field reference measurement

19.6 Effective frequency range

19.7 Internal latency

20 Directional characteristics

20.1 General

20.2 Direct sound field in 3D space

20.3 Directional far field characteristics

20.4 Acoustic output power

20.5 Sound power level

20.6 Mean acoustic output power in a frequency band

20.7 Radiation angle

20.8 Coverage angle or angles

20.9 Mean sound pressure level in an acoustical zone

21 Harmonic distortion

21.1 General

21.2 N^th-order harmonic component

21.3 Total harmonic components

21.3.1 Conditions to be specified

21.3.2 Method of measurement

21.4 Total harmonic distortion

21.4.1 Conditions to be specified

21.5 Higher-order harmonic distortion

21.6 Maximum sound pressure level limited by total harmonic distortion

21.7 N^th-order equivalent input harmonic distortion component

21.8 Equivalent input total harmonic distortion

22 Two-tone distortion

22.1 Variation of excitation frequencies

22.2 Modulation distortion

22.3 Amplitude modulation distortion

23 Multi-tone distortion

23.1 Conditions to be specified

23.2 Method of measurement

24 Impulsive distortion

24.1 Impulsive distortion level

24.2 Maximum impulsive distortion ratio

24.3 Mean impulsive distortion level

24.4 Crest factor of impulsive distortion

25 Stray magnetic fields

25.1 General

25.2 Static component

25.3 Dynamic components

Bibliography

BS EN IEC 60268-21:2018

Sound system equipment - Acoustical (output-based) measurements

Current

Published:

31 Jan 2019