IEC 62760:2016

IEC 62760 ®
Edition 1.1 2019-07
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
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Audio reproduction method for normalized loudness level

Méthode de reproduction audio pour niveau d'isosonie normalisé

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IEC 62760 ®
Edition 1.1 2019-07
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Audio reproduction method for normalized loudness level

Méthode de reproduction audio pour niveau d'isosonie normalisé

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.160.30 ISBN 978-2-8322-7175-9

IEC 62760 ®
Edition 1.1 2019-07
CONSOLIDATED VERSION
REDLINE VERSION
VERSION REDLINE
colour
inside
Audio reproduction method for normalized loudness level

Méthode de reproduction audio pour niveau d'isosonie normalisé

– 2 – IEC 62760:2016+AMD1:2019 CSV
© IEC 2019
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
INTRODUCTION to Amendment 1 . 6
1 Scope . 7
2 Normative references . 7
3 Terms, definitions and abbreviations . 7
3.1 Terms and definitions . 7
3.2 Abbreviations . 8
4 Loudness normalisation . 8
4.1 General . 8
4.2 System model . 8
4.3 Control method . 9
4.3.1 Principal control . 9
4.3.2 Optional control . 9
5 Channel mode . 10
5.1 General . 10
5.2 Input source . 10
5.3 1 channel mode . 11
5.4 2 channel mode . 12
5.5 5.1 multichannel stereophonic . 14
5.6 More than 5.1 channels . 14
6 Loudness level diagram . 15
6.1 General . 15
6.2 Reproduction level . 15
Annex A (informative) Loudness unit . 17
A.1 General . 17
A.2 Loudness quantity and unit . 17
Annex B (informative) Terms related to audio reproduction . 20
Annex C (informative) Loudness metadata . 22
Annex D (informative) Exception to loudness level diagram . 23
Annex E (informative) Example of case 6 . 24
Bibliography . 25

Figure 1 – System model . 9
Figure 2 – Input sources . 11
Figure 3 – 1 channel mode of reproduction . 11
Figure 4 – 2 channel mode of reproduction . 13
Figure 5 – 5.1 channel mode of reproduction . 14
Figure 6 – 22.2 channel mode for reproduction . 15
Figure E.1 – Reproduction level with respect to reference loudness level. 24

Table 1 – Reproduction level . 16
Table A.1 – Loudness quantity and unit . 18

© IEC 2019
Table D.1 – Reproduction level . 23
Table E.1 – Loudness level of samples . 24

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© IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
AUDIO REPRODUCTION METHOD FOR
NORMALIZED LOUDNESS LEVEL
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
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
This consolidated version of the official IEC Standard and its amendment has been
prepared for user convenience.
IEC 62760 edition 1.1 contains the first edition (2016-02) [documents 100/2591/FDIS and
100/2635/RVD] and its amendment 1 (2019-07) [documents 100/3184/CDV and 100/3241/
RVC].
In this Redline version, a vertical line in the margin shows where the technical content
is modified by amendment 1. Additions are in green text, deletions are in strikethrough
red text. A separate Final version with all changes accepted is available in this
publication.
© IEC 2019
International Standard IEC 62760 has been prepared by technical area 11: Quality for audio,
video and multimedia systems, of IEC technical committee 100: Audio, video and multimedia
systems and equipment.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of the base publication and its amendment will
remain unchanged until the stability 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.
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.
– 6 – IEC 62760:2016+AMD1:2019 CSV
© IEC 2019
INTRODUCTION
The loudness level of audio reproduction varies according to the level of the input source and
whether it is mono, stereo or multichannel. Without a suitable form of automatic control, users
are forced to adjust the volume level of equipment to obtain an appropriate loudness level
when the user selects another audio source or audio mode such as mono, stereo or downmix.
There are some specific adjustment methods applied to consumer equipment but these
methods are not standardized. For broadcast audio, broadcasting studios apply loudness
level measurements and settle a reference level for their audio content depending on
ITU-R BS.1770 and ITU-R BS.1864, the first standardisation work for loudness level in
broadcasting. The audio loudness levels of other services are also expected to be
standardized.
Broadcast audio with regulated loudness levels can be reproduced correctly with
appropriately-configured reproduction systems and equipment. This International Standard
specifies the method for reproduction with channel mode level setting and other level settings,
and provides improved quality of listening for users. This method is also applicable for various
audio content other than broadcasting audio. This International Standard is applicable to
electrical signal levels and excludes acoustic audio levels from loudspeakers.

INTRODUCTION to Amendment 1
The revision of IEC 62670:2016 is necessary in order to revise the informative information of
Annex C for the use of loudness metadata.

© IEC 2019
AUDIO REPRODUCTION METHOD FOR
NORMALIZED LOUDNESS LEVEL
1 Scope
This International Standard specifies the audio reproduction method for normalized loudness
level of audio sources for consumer equipment and systems.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 62574, Audio, video and multimedia systems – General channel assignment of
multichannel audio
ITU-R BS.1770-3:08/2012, Algorithms to measure audio programme loudness and true-peak
audio level
ITU-R BS.1770-4:10/2015, Algorithms to measure audio programme loudness and true-peak
audio level
3 Terms, definitions and abbreviations
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1.1
loudness
subjective notion describing the magnitude of the perception of the sound by the human
sense of hearing
Note 1 to entry: The magnitude of the auditory sensation mainly depends on sound pressure, it differs with
frequency and sustain time of sound (see ISO 226:2003).
Note 2 to entry: The loudness is based on a sound that is pure tone of 40 dB sound pressure level and 1 kHz
frequency, whose level is defined as 1 sone. Its symbol is N.
3.1.2
loudness level
level of a sound equal to the sound pressure level of 1 kHz sine wave
Note 1 to entry: The loudness level is sensed by humans as equal to the subjective sound level. The reference is
1 kHz sine wave and 40 dB sound pressure level, its loudness level is 40 phon.
Note 2 to entry: The symbol for loudness level is L and its unit is phon.
N
3.1.3
gated loudness
numerical value of loudness measured according to ITU‐R BS.1770‐3
Note 1 to entry: Gated loudness is measured in LKFS.

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© IEC 2019
3.1.4
LKFS
loudness, K-weighted, relative to nominal full scale
Note 1 to entry: LKFS is a unit whose value is defined in ITU-R Recommendation BS.1770-3.
Note 2 to entry: This note applies to the French language only.
3.1.5
monophonic
sound processing by a single channel
Note 1 to entry: Monophonic is a mode of recording audio with one microphone or an equivalent method,
transferring through one channel, then reproducing with one loudspeaker.
3.1.6
dual mono
consisting of two mono signal channels
Note 1 to entry: Dual mono is a mode of recording audio with two independent monophonic sounds, transferring
through two channels, then reproducing one of two signals.
3.1.7
stereophonic
sound processing by two or more related channels
Note 1 to entry: Stereophonic is a mode of recording audio with two or more microphones or an equivalent
method, transferring through two or more channels, then reproducing with two or more loudspeakers.
3.1.8
5.1 channel
stereophonic with 5 full range channels and 1 channel of low frequency effect
3.1.9
22.2 channel
stereophonic with 22 full range channels and 2 channels of low frequency effect
3.2 Abbreviations
mono monophonic
stereo stereophonic
4 Loudness normalisation
4.1 General
A system model is defined as specified below. It is applied to the back end of source devices
or the front end of amplifiers.
4.2 System model
Figure 1 describes the system model of reproduction. This model is applied to the appropriate
part of audio devices. For instance, a TV set may apply this model in its final stage of audio
reproduction, an audio amplifier may apply this model in its first stage of audio reproduction.

© IEC 2019
Audio
Channel mode
input
Audio mode
selection
Audio
Reproduced
Output
reference
level control
Metadata
(ur dB)
Downmix
To the gain
detection
gain
control of channel
control
mode
Metadata
(a ~ h dB) (dx dB)
input
Downmix
out
Optional
user
control
IEC
Figure 1 – System model
In this model, the channel mode applies the appropriate reproduction-level control described
in Clause 5. The downmix gain control is a compensation of reproduction level of downmix.
The reproduced reference level control is a final level control, it controls reproduction level to
the target reproduced reference level.
Metadata of loudness or other gain control information is input to the metadata detection.
They may be accompanied with audio data or separately input through other path. The
detected metadata shall be input to each gain control unit to control its function and gain
setting.
4.3 Control method
4.3.1 Principal control
The reproduction level of each channel mode is controlled as specified in Clauses 5 and 6.
The downmixed reproduction level is controlled by the downmix gain control. It is controlled
depending on the downmix mode by the manufacturer’s setting.
The reproduced reference level control controls the both downmix reproduction level and non-
downmix reproduction to the same reproduced reference level. The reproduced reference
level is settled by the manufacturer.
The metadata may be accompanied with audio data, or provided through other path such as
Internet or data distribution. These metadata shall be used to control reproduction levels of
the channel mode, downmix gain control and reproduced reference level control.
4.3.2 Optional control
For historical and practical reasons and situations in each country, it may be required to set a
specific reproduction level of channel modes and downmixes. The optional user control may
be applied to conform to these specific settings. The optional user control may be used by the
end user and the manufacturer.
The reproduction level of each channel mode is controlled as specified in Clause 6. Some
channel mode reproduction levels are not equal to the input level to the channel mode.
Reproduction levels of downmixes are not equal to the input level of the downmix gain control.

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© IEC 2019
Channel mode controls the reproduction level depending on the manufacturer’s mode settings
or the optional user control, and it can also be controlled with the metadata.
The downmixed reproduction level is controlled by the downmix gain control to be equal to the
input level of the downmix gain control. It is controlled depending on the downmix mode by
the manufacturer setting or by the optional user control, and it can also be controlled with the
metadata.
The metadata may be accompanied with audio data, or may be provided through another path
such as Internet or data distribution.
The reproduced reference level control controls the downmix reproduction level and non-
downmix reproduction to be the target reproduced reference level, the target reproduced
reference level is settled by the manufacturer or by the user setting the optional user control,
and it can also be controlled with the metadata.
5 Channel mode
5.1 General
Channel mode defines the reproduction method and level of each channel in conjunction with
the input source for each channel. Channels may range from monophonic to many channels
stereophonic, and input sources may range from monophonic to many channels stereophonic.
5.2 Input source
The combination of channels and input sources is shown in Figure 2. These show sets of
possible input sources for each channel mode. These input sources are identified as S1 to S5.
S5 is a case of more than 5.1 channels that applies the general channel assignment defined
by IEC 62574.
S1, with content A, is 1 channel input source to M1 or M2.
S2, with content AL and AR, is 2 channel input source of the stereophonic or the same
input source to L and R.
S3, with content A and B, is 2 channel input source of the two independent input sources
to L and R., e.g. bilingual application.
S4, with content AL, AR, AC, ALFE, ALS and ARS, is 5.1 channel input source of the 5.1
channel stereophonic input source to L to RS.
S5, with content AFL, AFR, and ABtFR, is 22.2 channel input source of the 22.2 channel
stereophonic input source to FLc to BtFR.

© IEC 2019
Channels       S1 S2 S3 S4 S5
L （M１ for S1）
A AL A AL AFL
R （M2 for S1）
A
AR B AR AFR
C
AC AFC
LFE
ALFE ALFE1D
LS
ALS ABL
RS
ARS ABR
FLc
AFLcG
BtFR
ABtFR
IEC
Figure 2 – Input sources
5.3 1 channel mode
In the 1 channel mode, one channel reproduces one or two input sources. Figure 3 shows
various cases for 1 channel mode of reproduction.
S1
Case 1
L/R a dB
A
S2
AL
L
Case 2
b dB
+
AR
R
S3
A L
Case 3
c dB
B R
IEC
Figure 3 – 1 channel mode of reproduction

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© IEC 2019
In cases where the output sound is reproduced by two or more loudspeakers, the level should
be controlled to maintain the same level of reproduction as one loudspeaker.
In each case, the level attenuator should be set as follows:
Case 1, a = 0 dB
Case 2, b = −3 dB
Case 3, c = 0 dB
Case 2 should consider headroom when each input reference is over −24 LKFS.
5.4 2 channel mode
In the 2 channel mode, stereophonic or monophonic content and channel mode of
reproduction is defined, as shown below. Figure 4 shows various cases for 2 channel mode of
reproduction.
© IEC 2019
d dB
S1
Case 4 A
L/R
d dB
S2
AL e dB
L
Case 5a
AR
e dB
R
S3
A
e dB
L
Case 5b
B e dB
R
S3
A
L f dB
Case 6
+
B R
f dB
S3
A
g dB
L
Case 7
B
R g dB
IEC
Figure 4 – 2 channel mode of reproduction
In each case, the level attenuator should be set as follows:
Case 4, d = −3 dB
Case 5a, e = 0 dB
Case 5b, e = 0 dB
Case 6, f = −5 dB
Case 7, g = −3 dB
– 14 – IEC 62760:2016+AMD1:2019 CSV
© IEC 2019
NOTE 1 Case 5b level is defined considering a hearing level of content A and B from two loudspeakers.
NOTE 2 Case 6 mostly reproduces content A and B with a correlation coefficient from 1 to 0, see Annex E.
5.5 5.1 multichannel stereophonic
5.1 channels content and channel modes of reproduction are defined, as shown below.
Figure 5 shows channel mode of reproduction.
S4
L 1 channel mode and 2 channel mode
AL
are applied.
R
AR
1 channel mode is applied.
AC
C
Case 8
ALFE
LFE
h dB
ALS
LS
ARS
RS
S4
AL
L
AR
R
AC
C
Case 9
downmix
LS
ALS
ARS
RS
ALFE
LFE
IEC
Figure 5 – 5.1 channel mode of reproduction
In Case 8, the level attenuator should be set as follows:
Case 8, h = +10 dB
5.6 More than 5.1 channels
22.2 channels content and channel mode of reproduction is defined as shown below. Figure 6
shows channel mode of reproduction.

© IEC 2019
C5
1 channel mode and 2 channel mode
AFL
FL
are applied.
AFR
FR
1 channel mode is applied.
AFC
FC
Case 10
ALFE1D
LFE1
h dB
ABtFR BtFR
C5
AFL
FL
Case 11
downmix
ABtFR BtFR
IEC
Figure 6 – 22.2 channel mode for reproduction
In Case 10, the level attenuator should be set as follows:
h = +10 dB
6 Loudness level diagram
6.1 General
This clause specifies the audio reproduction level of the system model. The reference gated
loudness of the audio input source is −24 LKFS (see Annex A), the target reproduced
reference level is specified depending on that input reference.
6.2 Reproduction level
In each channel mode, the input source and reference gated loudness and target reproduced
reference level is shown in Table 1.

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© IEC 2019
Table 1 – Reproduction level
Input source and Transfer / Reproduction of 2 Target reproduced
reference gated channel mode channel stereo reference level
loudness
Monophonic 1 channel / mono Case 1
−24 LKSF
−24 LKFS Case 4
Dual mono 2 channel / dual mono Case 3 −24 LKFS
−24 LKFS Case 5b
per channel
Case 6
Case 7
2 channel stereophonic 2 channel / stereo Case 2
−24 LKFS
Case 5a
−24 LKFS
5.1 channel 5.1 channel / Case 8 −24 LKFS
5.1 channel
−24 LKFS
5.1 channel /
Case 9 −24 LKFS
downmix
22.2 channel 22.2 channel / Case 10
−24 LKFS
22.2 channel
−24 LKFS
22.2 channel / Case 11
−24 LKFS
downmix
In each mode, target reproduced reference levels are specified as follows:
a) Mono −24 LKFS
b) Dual mono L = −24 LKFS, R = −24 LKFS
c) Stereo L + R = −24 LKFS
d) 5.1 channel 5 channel total = −24 LKFS
e) 22.2 channel 22 channel total = −24 LKFS
NOTE For historical reasons mono has another setting. This setting is described in Annex D.

© IEC 2019
Annex A
(informative)
Loudness unit
A.1 General
The sense of hearing has a frequency characteristic as defined by ISO 226:2003. Loudness is
a quantity name of that sense of hearing, the unit name is sone.
1 sone = 40 phon = 40 dB (sound pressure level) at 1 kHz pure tone
Loudness level means a level on a logarithmic scale of loudness. This specification uses the
unit name LKFS that is defined in Recommendation ITU-R BS.1770-3. ISO 226:2003 has a
different measurement, and uses the unit name phon for the quantity name loudness level.
The LKFS is used for the measurement of recorded loudness of broadcast audio programme
materials. It uses gated loudness as its quantity name. A recorded audio signal loudness level
is measured by the algorithm defined by Recommendation ITU-R BS.1770-3 which is based
on subjective loudness.
A.2 Loudness quantity and unit
The terms loudness and loudness level are used for the two cases. The first is used for
general terms of the expression of sound level, the second is used for a quantity name of the
kind of sound level. A numerical amount should identify what kind of amount it expressed, for
instance, sone, phon and unit name LKFS. Though dB is used for many kinds of amounts, it
should be used with the quantity name or quantity symbol. In case of using LKFS or phon, it
should be used with conformance to the quantity name or quantity symbol.

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© IEC 2019
Table A.1 – Loudness quantity and unit
Measurement of loudness
Quantity Unit
Description
Name Symbol Definition Name Symbol
The sound level that the human
hearing perceives, mainly depends
on sound pressure. It differs with
frequency and length of time of the
sound (see ISO 226:2003).
The loudness is based on a sound
L > 40 phon
N
that is a pure tone of 40 dB sound
0,3
pressure level and 1 kHz
L
 
N – 40
frequency, whose level is defined
 
L – 40
N
N= 10 ≈ 2 as 1 sone as its unit and its
 
Loudness N sone －
quantity symbol is N.
 
 
A sound of 2 sone is sensed as

subjectively twice as loud as a

sound of 1 sone.
The method for calculation of
loudness of a steady tone (steady
sound) is defined by ISO 532.
The method utilizes a 1/3 octave
analyser and a chart.
ITU-R BS.1770-3: Method of
L = –0,691+ 10lg G
KG ∑ i
measurement of recorded
i
loudness of broadcast audio
programme material.
 
 1 
The gated loudness level (L ) is a
× × Zij
KG
 ∑ 
K-weighted and time-weighted
J
 
g
J
g
 
sound level with gated loudness
Gated
a
L LKFS (400 ms windows, absolute and
KG
i∈ I,I={L,R,C,Ls,Rs}
loudness
relative threshold) and channel
gain weighting.
G : weighting coefficient for
i
channels
1 LKFS is equal to 1 dB.
J : gating threshold
g
Z : gating block loudness for
ij
channels
ITU-R BS.1770-3: Method of
measurement of recorded
L = –0,691+10lg G × Z
K ∑ i i
loudness of broadcast audio
i
programme material.
Loudness
i∈ I,I={L,R,C,Ls,Rs}
a
L LKFS The non-gated loudness level (L )
(non- gated K K
is a K-weighted and time-weighted
G : weighting coefficient for
loudness)
i
sound level with channel gain
channels
weighted.
Z : loudness for channels
i
1 LKFS is equal to 1 dB.
The value equal to the sound
pressure level of 1 kHz sine wave,
is sensed by a human as equal to
the subjective sound level.
 P 
eff
 
L = ln 1 kHz
N
Symbol is L ; unit is phon.
 
N
P
 
The reference is a 1 kHz sine
Loudness
L phon －
p = 20 µPa
N wave at 40 dB sound pressure, its
level
loudness level is 40 phon.
: root-mean-square value of
p
eff
the sound pressure of a pure The graph of each frequency that
tone of 1 kHz is sensed as the same sound level
as a 1 kHz sine wave, is given in
ISO 226:2003, Normal equal-
loudness level contours.
© IEC 2019
Measurement of loudness
Quantity Unit
Description
Name Symbol Definition Name Symbol
ISO 21727: Method of
 
P measurement of perceived
 
L = 20lg
eq(M)
loudness of motion-picture audio
 
P
 0
material.
Loudness
equivalent L decibel dB
p = 20 µPa
eq(M) Measure the mean of the scalar
level
sum over the duration of the sound
p: root-mean-square value of the
recording. M-weighted is a curve of
sound pressure, of the M-
the ITU-R BS.468-4 with 5,6 dB
weighted measurement
offset weighting.
IEC 61672-1: This standard is
L = 20lg
AT
intended to measure sounds
generally in the range of human
1/ 2
 
t
 1 
  hearing.
P (ξ)dξ
A
 
∫
 
t –T
T
 
Equivalent continuous A-weighted
×
 
sound pressure level.
A-weighted P
 
and time-
 
L decibel dB
Aeq,T
average
 
sound level
ξ : variable of integration
p = 20 µPa
p measured value of A-
A:
weighted sound pressure
a
Loudness, K-weighted, relative to nominal full scale.

– 20 – IEC 62760:2016+AMD1:2019 CSV
© IEC 2019
Annex B
(informative)
Terms related to audio reproduction
Additional terms and definitions regarding loudness are listed below.
B.1
equal-loudness contours
graph of each frequency that is sensed as the same loudness of 1 kHz sine wave, as
specified in ISO 226:2003
B.2
phon
unit of loudness level, judged or calculated as specified in the definition of "loudness level" or
"calculated loudness level" defined in ISO 532
B.3
sone
unit of loudness, equal to the loudness of a pure tone presented frontally as a plane wave of
frequency 1 000 Hz and a sound pressure level of 40 dB, with a reference of 20 μPa
Note 1 to entry: Any other than sine wave sound is calculated by the method defined in ISO 532.
Note 2 to entry: The loudness of a sound judged by the listener to be n times that of the 1-sone tone is n sones.
B.4
integrated loudness
calculated loudness of a given period of digital recording data depending on the algorithm
defined in ITU-R Recommendation BS.1770-3
B.5
programme loudness
integrated loudness on full programme duration
B.6
target loudness
target level of programme loudness used to keep the hearing level of a programme
B.7
LU
loudness (level) unit for differences between loudness levels
B.8
dialogue level
loudness level of a typical dialogue contained in a programme
Note 1 to entry: A "typical" dialogue is that spoken in a normal tone of voice, i.e. neither shouted or whispered.
The average loudness level of all dialogue in a programme can be considered the "dialogue level", from which the
"typical" dialogue can be isolated and measured.
B.9
normalize
adjust various loudness values of a programme to a reference level
B.10
downmix
render over three channels of audio signals on two or one channel(s)

© IEC 2019
Note 1 to entry: Generally, it is used to render a 5.1 channel surround sound on 2 channel stereo.
B.11
audio mode
type of audio recording or transmission
EXAMPLES Mono, stereo and surround.
B.12
2 channel stereophonic with mono source
mono-stereophonic
mode of recording audio with one microphone or equivalent method, by dividing it into two
channels with the same phase and level, transferring through two channels, then reproducing
with two loudspeakers
B.13
dual mono
mode of recording audio of two independent monophonic sounds, transferring through two
channels, then reproducing one of two signals
B.14
bi-lingual
transfer two different language contents at the same time in one programme
Note 1 to entry: In case of dual-mono mode, two independent channels are carried in one audio stream. In case
of 2ADTS (Audio Data Transport Stream) mode, each channel is carried by each audio stream.
B.15
monaural
sound reception by one ear
– 22 – IEC 62760:2016+AMD1:2019 CSV
© IEC 2019
Annex C
(informative)
Loudness metadata
Loudness metadata is information on the loudness of audio content. Information on loudness
is specified by EBU – TECH 3285, Specification of the Broadcast Wave Format (BWF) – A
format for audio data files in broadcasting, Version 2.0.
Metadata is defined as follows:
LoudnessValue A 16-bit signed integer, equal to round(100x the Integrated
Loudness Value of the file in LUFS)
LoudnessRange A 16-bit signed integer, equal to round(100x the Loudness
Range of the file in LU)
MaxTruePeakLevel A 16-bit signed integer, equal to round(100x the Maximum True
Peak Value of the file in dBTP)
MaxMomentaryLoudness A 16-bit signed integer, equal to round(100x the highest value of
the Momentary Loudness Level of the file in LUFS)
MaxShortTermLoudness A 16-bit signed integer, equal to round(100x the highest value of
the Short-term Loudness Level of the file in LUFS)
NOTE LUFS is specified by EBU, it is a synonym for LKFS.
Loudness metadata provides information on the loudness of audio content. Information on
loudness is specified by Recommendation ITU-R BS.2076, which defines loudness metadata
that can be included in a Broadcast Wave 64-bit file (BW64) as defined by Recommendation
ITU-R BS.2088. Broadcast Wave Format (BWF) files are specified by EBU Tech 3285, which
defines the carriage of loudness metadata defined in EBU Tech 3364, which is a mirror copy
of ITU-R BS.2076. Therefore, the loudness metadata parameters defined below can be
carried in both BWF and BW64 files.
Metadata is defined as follows.
The integrated loudness value of the programme using the measurement
integratedLoudness
method described by loudnessMethod in LKFS.
loudnessRange The loudness range of the programme in LU.
maxTruePeak The maximum true peak level of the programme in dBTP.
maxMomentary The maximum momentary loudness value of the programme in LKFS.
maxShortTerm The maximum short-term loudness value of the programme in LKFS.
dialogLoudness The average loudness of the dialog in the programme in LKFS.
loudnessMethod The method or algorithm used to calculate the loudness indicated above.
Typically, this will be “BS1770”.
loudnessRecType The regional recommended practice that was followed in the loudness
measurement/correction of the programme. For example, ATSC A/85, EBU
R128.
loudnessCorrectionType The correction type that was used to correct the programme, either an offline
file-based correction method, or a real-time method.

The unit "LKFS" is the loudness defined in ITU-R BS.1770, whereas the EBU uses "LUFS",
and both may be used as defined in ITU-R BS.2076.

© IEC 2019
Annex D
(informative)
Exception to loudness level diagram
Clause 5 described a loudness level diagram for reproduction level. However, in some
broadcasting cases within a region, a practical level is applied to content reference loudness
level.
Table D.1 shows that the 1- and 2-channel mono content is levelled to a practical level. In this
case, the target reproduction level should be the same reference level as −24 LKFS.
To obtain the same reference level, the optional control method can be applied.
Table D.1 – Reproduction level
Input source and Transfer / Reproduction of Target reproduced
reference loudness channel mode 2 channel stereo reference level
level
1 channel mono (M) 1 channel / mono Case 1
−24 LKFS
Case 4
−27 LKFS
as practical
2 channel mono (M) 2 channel / – Case 2 −24 LKFS
Case 5a
−27 LKFS
as practical
NOTE Broadcast audio in Japan has 2 channel mono mode which provides the same mono content in both
channels.
– 24 – IEC 62760:2016+AMD1:2019 CSV
© IEC 2019
Annex E
(informative)
Example of case 6
When case 6 reproduces dual-mono content, the reproduction loudness level varies
depending on its content.
For example, the following contents are reproduced.
– Sample 1, includes an in-phase piano sound component, different language bilingual
– Sample 2, includes an in-phase piano sound component, different language bilingual
– Sample 3, includes an in-phase piano sound component, same language independent
– Sample 4, includes an in-phase piano sound component, same language independent
– Sample 5, excludes an in-phase component, same content as sample 1
– Sample 6, excludes an in-phase component, same content as sample 3
Piano sound level of each sample 1 to 4 is set as sample 1 > sample 2 > sample 3 > sample 4.
Each sample's loudness level is shown in Table E.1.
Table E.1 – Loudness level of samples
Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6
LKFS LKFS LKFS LKFS LKFS LKFS
L channel −24,0 −24,0 −24,0 −24,0 −24,0 −24,0
R channel
−24,0 −24,0 −24,0 −24,0 −24,0 −24,0
Stereo
−21,0 −21,0
...