IEC 60268-23:2023

IEC 60268-23 ®
Edition 1.0 2023-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Sound system equipment –
Part 23: TVs and monitors – Loudspeaker systems

Équipements pour systèmes électroacoustiques –
Partie 23: Téléviseurs et moniteurs – Systèmes de haut-parleurs

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IEC 60268-23 ®
Edition 1.0 2023-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Sound system equipment –
Part 23: TVs and monitors – Loudspeaker systems

Équipements pour systèmes électroacoustiques –

Partie 23: Téléviseurs et moniteurs – Systèmes de haut-parleurs

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.160.01; 33.160.50 ISBN 978-2-8322-6548-2

– 2 – IEC 60268-23:2023 © IEC 2023
CONTENTS
FOREWORD . 7
INTRODUCTION . 9
1 Scope . 10
2 Normative references . 10
3 Terms, definitions and abbreviated terms . 10
3.2 Abbreviated terms . 11
4 Type description . 12
5 Physical characteristics . 12
5.1 Dimensions . 12
5.2 Mass . 12
6 Conditions . 12
6.1 Normal measuring conditions . 12
6.2 Rated conditions . 13
6.3 Rated frequency range . 13
6.4 Climatic conditions . 13
7 Test signals . 13
7.1 General . 13
7.2 Sinusoidal chirp signal . 13
7.3 Steady-state single-tone signal . 13
7.4 Steady-state two-tone signal . 14
7.5 Sparse multi-tone complex . 14
7.6 Broadband noise signal . 14
7.7 Narrow-band noise signal . 14
7.8 Hann-burst signal . 14
7.9 Impulsive signal . 14
8 Acoustical environment . 14
8.1 General . 14
8.2 Free-field conditions . 14
8.3 Simulated free-field conditions . 14
8.4 In-situ environment . 15
8.5 Listening room . 15
9 Measurement equipment . 15
10 Positioning of the EUT . 15
10.1 Reference plane and normal vector . 15
10.2 Reference point . 15
10.3 Reference axis . 16
10.4 Orientation vector . 16
10.5 Horizontal and Vertical Trajectories . 18
11 Measuring distance between EUT and microphone . 18
11.1 Far-field conditions . 18
11.2 Near-field conditions . 18
12 Mounting of the EUT . 19
12.1 General . 19
12.2 Mounting methods . 19
12.2.1 Stand-type . 19

12.2.2 Wall mount-type . 19
12.3 Mounting for free-field conditions . 20
12.3.1 General . 20
12.3.2 EUT rotating condition . 20
12.3.3 Microphone rotating condition . 20
13 Rated ambient conditions . 20
13.1 Temperature ranges . 20
13.1.1 Performance limited temperature range . 20
13.1.2 Damage limited temperature range . 21
13.2 Humidity ranges . 21
13.2.1 Relative humidity range . 21
13.2.2 Damage limited humidity range . 21
14 Evaluation point and distance . 21
14.1 Evaluation point . 21
14.2 Evaluation distance . 21
15 Free-field measurements . 22
15.1 General . 22
15.2 On-axis SPL FR . 22
15.2.1 Definition . 22
15.2.2 Measurement methods . 22
15.2.3 Reporting . 22
15.3 Spatial transfer function . 23
15.3.1 Definition . 23
15.3.2 Measurement method . 23
15.3.3 Reporting . 24
15.4 Sound power response . 24
15.4.1 Definition . 24
15.4.2 Measurement methods . 25
15.4.3 Reporting . 25
15.5 Directional characteristics . 26
15.5.1 General . 26
15.5.2 Measurement methods . 27
15.5.3 Post-processing . 27
15.5.4 Reporting . 30
16 In-situ testing . 30
16.1 General . 30
16.2 In-situ transfer function . 31
16.2.1 Definition . 31
16.2.2 Measurement method . 32
16.2.3 Reporting . 33
16.3 Room transfer function . 33
16.3.1 Definition . 33
16.3.2 Measurement method . 33
16.4 Reflected sound SPL response . 34
16.4.1 Definition . 34
16.4.2 Measurement method . 34
16.4.3 Reporting . 35
16.5 In-situ SPL FR . 35

– 4 – IEC 60268-23:2023 © IEC 2023
16.5.1 Definition . 35
16.5.2 Measurement methods . 35
16.5.3 Reporting . 36
17 Mean SPL in an acoustical zone . 37
17.1 General . 37
17.2 Definition . 37
17.3 Measurement . 38
17.4 Numerical prediction . 38
17.5 Reporting . 38
18 FR characteristics . 38
18.1 General . 38
18.2 Mean value of SPL in a rated frequency range . 39
18.2.1 Definition and unit . 39
18.2.2 Setup . 39
18.2.3 Procedure . 39
18.2.4 Analysis . 39
18.2.5 Reporting . 40
18.3 Effective frequency range (EFR) . 40
18.3.1 Definition and unit . 40
18.3.2 Setup . 40
18.3.3 Procedure . 40
18.3.4 Analysis . 41
18.3.5 Reporting . 41
18.4 Spectral balance (SB) . 42
18.4.1 Definition and unit . 42
18.4.2 Setup . 42
18.4.3 Procedure . 42
18.4.4 Analysis . 42
18.4.5 Reporting . 43
18.5 Regression line deviation (RLD) . 43
18.5.1 Definition and unit . 43
18.5.2 Setup . 43
18.5.3 Procedure . 43
18.5.4 Analysis . 44
18.5.5 Reporting . 44
18.6 Narrow band variation (NBV) . 45
18.6.1 Definition and unit . 45
18.6.2 Setup . 45
18.6.3 Procedure . 45
18.6.4 Analysis . 45
18.6.5 Reporting . 46
19 Large-signal characteristics . 46
19.1 Modelling at high amplitudes . 46
19.2 Noise spectrum . 47
19.2.1 Definition and measurement . 47
19.2.2 Reporting . 47
19.3 Short-term amplitude compression . 47
19.3.1 Definition and unit . 47
19.3.2 Setup . 47

19.3.3 Procedure . 47
19.3.4 Analysis . 48
19.3.5 Reporting . 48
19.4 Multi-tone distortion . 48
19.4.1 Multi-tone distortion spectrum . 48
19.4.2 Absolute multi-tone distortion . 50
19.4.3 Relative multi-tone distortion . 51
19.4.4 Total multi-tone distortion ratio . 52
19.5 Harmonic distortion in sound pressure output . 53
19.5.1 Definition and unit . 53
19.5.2 Setup . 54
19.5.3 Procedure and analysis . 54
19.5.4 Reporting . 55
19.6 Equivalent input total harmonic distortion . 56
19.6.1 Definition and unit . 56
19.6.2 Setup . 57
19.6.3 Procedure . 57
19.6.4 Analysis . 57
19.6.5 Reporting . 58
19.7 Impulsive distortion . 59
19.7.1 Definition and unit . 59
19.7.2 Setup . 59
19.7.3 Procedure . 59
19.7.4 Analysis . 59
19.7.5 Reporting . 60
19.8 Rated maximum input value . 60
19.8.1 Definition and unit . 60
19.8.2 Setup . 60
19.8.3 Procedure . 61
19.8.4 Analysis . 62
19.8.5 Reporting . 62
19.9 Rated maximum SPL . 62
19.9.1 Definition and unit . 62
19.9.2 Setup . 62
19.9.3 Procedure . 62
19.9.4 Reporting . 63
Bibliography . 64

Figure 1 –Test signal scope . 12
Figure 2 –Recommended position and orientation of the EUT . 16
Figure 3 – Measuring the horizontal directivity in spherical coordinates by rotating the
EUT (e.g., OLED TV) in upright position. 17
Figure 4 – Measuring the vertical directivity in spherical coordinates by rotating the

tilted EUT (e.g. OLED TV) . 17
Figure 5 – Example for stand-type . 19
Figure 6 – Example for wall mount-type. . 20
Figure 7 – Evaluation point and distance (centre) . 21
Figure 8 – SPL distribution of the direct sound represented in colour in 3D . 24

– 6 – IEC 60268-23:2023 © IEC 2023
Figure 9 – Measurement locations at vertical and horizontal trajectories at distance r . 26
d
Figure 10 – Measurement locations at listening window . 28
Figure 11 – Measurement locations at equivalent sound power . 29
Figure 12 – Example for reporting the directional characteristics measured
at distance r . . 30
d
Figure 13 – Modelling the sound reproduction under in-situ conditions . 32
Figure 14 – Example of time-frequency analysis (spectrogram) applied to reflected
sound impulse response ht(,r) measured at a distance r = 1,5 m from the EUT in
REFL
an office room . 33
Figure 15 – SPL FR of the in-situ condition. . 36
Figure 16 – Mean value of SPL at rated frequency range . 40
Figure 17 – Effective Frequency Range at Frequency Response . 41
Figure 18 – Regression line deviation at rated frequency range . 44
Figure 19 – Loudspeaker model considering the dominant signal distortion at high
amplitudes . 46
Figure 20 – SPL spectrum of the reproduced multi-tone stimulus (MDS) at full FFT
resolution comprising the fundamental components at the excited tones and the
distortion components at other frequencies . 49
Figure 21 – SPL of the fundamental, multi-tone distortion and noise floor integrated
into frequency bands at the excitation frequencies of the multi-tone stimulus . 51
Figure 22 – Relative multi-tone distortion Lf() and relative noise floor Lf() in
RMD i RNF i
decibel versus excitation frequencies f . . 52
i
Figure 23 – Total harmonic distortion (THD) referred to the fundamental component
measured at three distances on the reference axis . 55
Figure 24 – SPL FR of the fundamental component, total harmonic components (
Lf(,r ) ), and the noise floor Lf(,r ) . 56
TH e NFTH e
Figure 25 – Signal flow chart illustrating the generation of the equivalent input
distortion by inverse filtering the sound pressure signal measured at three different
points in an in-situ environment (office). 57
Figure 26 – Equivalent input total harmonic distortion (EITHD) in percent versus
excitation frequency measured at three distances on the reference axis in an in-situ
environment . 58

Table 1 – Recommended coordinates of the trajectories at distance r . 18
D
Table 2 – Evaluation distance reference standard . 22
Table 3 – Weights for polar angle θ at 10° Increments . 29
Table 4 – Worked example for mean value of SPL . 40
Table 5 – Worked example for effective frequency range . 41
Table 6 – Worked example for spectral balance . 43
Table 7 – Worked example for RLD. 44
Table 8 – Worked example for NBV . 46
Table 9 – Worked example for rated maximum input value . 62
Table 10 – A Worked example for Rated maximum SPL . 63

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SOUND SYSTEM EQUIPMENT –
Part 23: TVs and monitors – Loudspeaker systems

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
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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
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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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
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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.
IEC 60268-23 has been prepared by technical area 20: Analogue and digital audio, of IEC
technical committee 100: Audio, video and multimedia systems and equipment. It is an
International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
100/3774/CDV 100/3831/RVC
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
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.

– 8 – IEC 60268-23:2023 © IEC 2023
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under 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 document 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
IEC TC 100 has already standardized loudspeaker measurement methods. However, the
locations of the loudspeakers of TVs and monitors vary (e.g. front, bottom, back, side), and TVs
and monitors are used on stands or wall-mounted, and methods used for their installation
continue to evolve. Since the sound characteristics change according to the installation type
and position of the loudspeaker, it is necessary to develop new measurement methods for
loudspeakers of TVs and monitors. This document provides measurement methods for the audio
system of TVs and monitors that take into account the listening environment.

– 10 – IEC 60268-23:2023 © IEC 2023
SOUND SYSTEM EQUIPMENT –
Part 23: TVs and monitors – Loudspeaker systems

1 Scope
This part of IEC 60268 specifies acoustical measurement methods that apply to TV sets,
monitors with built-in loudspeakers, and other audio devices having similar acoustical properties
(e.g. flat-panel loudspeakers). The acoustical measurements are performed under free-field
conditions and in-situ.
This document does not assess the perception and cognitive evaluation of the reproduced
sound, nor the impact of perceived sound quality.
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 60268-2:1987, Sound system equipment – Part 2: Explanation of general terms and
calculation methods
IEC 60268-21:2018, Sound system equipment – Part 21 Acoustical (output-based)
measurements
IEC 61094-4, Measurement microphones – Part 4: Specifications for working standard
microphones
IEC 61260-1:2014, Electroacoustics – Octave-band and fractional-octave-band filters – Part 1:
Specifications
ISO 3744, Acoustics – Determination of sound power levels and sound energy levels of noise
sources using sound pressure – Engineering methods for an essentially free field over a
reflecting plane
ISO 3745, Acoustics – Determination of sound power levels and sound energy levels of noise
sources using sound pressure – Precision methods for anechoic rooms and hemi-anechoic
rooms.
ISO 80000-2, Quantities and units – Part 2: Mathematics
ANSI/CTA 2034-A:2015, Standard Method of Measurement for In-Home Loudspeakers
3 Terms, definitions and abbreviated terms
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
equipment under test
EUT
equipment to be measured using the methods described in this document
3.2 Abbreviated terms
For the purposes of this document, the following abbreviated terms apply.
COG centre of gravity
dB decibel
DEF direct energy fraction
DNR distortion-to-noise ratio
DSP digital signal processor
EFR effective frequency range
EITHD equivalent input total harmonic distortion
ESP equivalent sound power
ESPDI equivalent sound power directivity index
EUT equipment under test
FR frequency response
Hz hertz
m metre
MD absolute multi-tone distortion
MDS multi-tone distortion spectrum
NBV narrow band variation
NF noise floor
ON on-axis FR
Pa  pascal
POR point of rotation
RFR rated frequency range
RLD regression line deviation
RMS root mean square
RMD relative multi-tone distortion
RNF relative noise floor
SB spectral balance
SNR signal-to-noise ratio
SP sound power
SPL sound pressure level
TFA time-frequency analysis
TH total harmonic
THD total harmonic distortion
TMDR total multi-tone distortion ratio
W watt
– 12 – IEC 60268-23:2023 © IEC 2023
4 Type description
The type description, which includes the following information, shall be provided by the
manufacturer.
a) Number of input channels: typically, the EUT has two input channels that excite at least one
transducer on both the left-hand side and the right-hand side, as shown in Figure 1. The
configuration shall be clearly specified for EUTs with more input channels.
b) Signal input format: for example, analogue, digital and wireless.
c) Type, principles, and the number of the transducers used in the TV and monitor audio
systems.
d) Power amplification of audio.
e) DSP (e.g. equalizer, active protection).

Figure 1 –Test signal scope
5 Physical characteristics
5.1 Dimensions
The outer dimensions of the EUT should be specified.
5.2 Mass
The total mass of the EUT should be specified.
6 Conditions
6.1 Normal measuring conditions
The EUT shall be understood to be under normal measuring conditions if all of the following
conditions are met.
a) The acoustical environment is specified and selected from those given in Clause 8.
b) Unwanted acoustical signals, electrical signals, and noise generated by other sources shall
be kept at the lowest levels possible because their presence may obscure low-level signals.
Data related to signals, which are less than
...