IEC 60263:2020

Scales and sizes for plotting frequency characteristics and polar diagrams

IEC 60263:2020 specifies standard aspect ratios for logarithmic or level characteristics expressed in decibels versus a logarithmic frequency axis and ranges for the radius of polar diagrams of level. Applications include hard copy printouts, electronic files (e.g., PDF files), scientific publications, screen displays in computer programs and apps, as well as graphs in standards.
Informative examples of graphs that conform to the requirements in this document are found in Annex A.
Although outside the scope of this document, graphs with a linear y-axis versus logarithmic frequency (e.g., phase, group delay, etc.) often accompany the standard aspect ratio graphs of level described in the normative part of this document. These are described in informative Annex B.
IEC 60263:2020 cancels and replaces the third edition published in 1982. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) the scope is expanded to include electronic files (e.g., PDF), scientific publications, graphs in other standards, and screen displays in programs and apps;
b) a Terms and Definitions clause has been added;
c) aspect ratios of 20 dB/decade, and 0,5, 1, 1,25, and 2,5 decades/decade have been added;
d) ranges of 60 dB or 30 dB are specified for polar plots of absolute level; a 30 dB range is specified for polar plots of relative level;
e) as most graphs are now computer generated, tolerances and sizes have been removed;
f) all informative figures have been updated with contemporary examples;
g) an informative annex with information about linear y-axis vs. logarithmic frequency has been added.

Échelles et dimensions des graphiques pour le tracé des courbes de réponse en fréquence et des diagrammes polaires

L'IEC 60263:2020 spécifie les formats normalisés des caractéristiques logarithmiques ou de niveau exprimées en décibels en fonction d'un axe de fréquence logarithmique et des domaines de variation du rayon des diagrammes polaires de niveau. Les applications incluent les copies papier, les fichiers électroniques (fichiers PDF, par exemple), les publications scientifiques, les affichages à l'écran des programmes et applications, ainsi que les graphiques dans les normes.
Des exemples de graphiques conformes aux exigences du présent document sont donnés à l'Annexe A.
Bien qu'ils n’entrent pas dans le domaine d'application du présent document, les tracés avec un axe y linéaire en fonction d'une fréquence logarithmique (par exemple phase, temps de propagation de groupe, etc.) accompagnent souvent les graphiques de format normalisé du niveau décrit dans la partie normative du présent document. Ces tracés sont décrits à l'Annexe B (informative).
L'IEC 60263:2020 annule et remplace la troisième édition parue en 1982. Cette édition constitue une révision technique.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) le domaine d'application a été élargi pour intégrer des fichiers électroniques (PDF, par exemple), des publications scientifiques, des graphiques d'autres normes et des affichages à l'écran des programmes et applications;
b) un article Termes et définitions a été ajouté;
c) les formats 20 dB/décade, et 0,5, 1, 1,25 et 2,5 décades/décade ont été ajoutés;
d) des plages de 60 dB ou 30 dB ont été spécifiées pour les diagrammes polaires de niveau absolu; une plage de 30 dB a été spécifiée pour les diagrammes polaires de niveau relatif;
e) la plupart des graphiques étant aujourd'hui générés par ordinateur, les tolérances et dimensions ont été supprimées;
f) toutes les figures informatives ont été mises à jour avec des exemples contemporains;
g) une annexe informative contenant des informations relatives à l'axe y linéaire en fonction de la fréquence logarithmique a été ajoutée.

General Information

• Status: Published
• Publication Date: 25-Jun-2020
• ICS: 17.140.50 - Electroacoustics
• Technical Committee: TC 29 - Electroacoustics
• Drafting Committee: MT 25 - TC 29/MT 25
• Current Stage: PPUB - Publication issued
• Start Date: 26-Jun-2020
• Completion Date: 10-Jul-2020

Standards Content (Sample)

IEC 60263 ®
Edition 4.0 2020-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Scales and sizes for plotting frequency characteristics and polar diagrams

Échelles et dimensions des graphiques pour le tracé des courbes de réponse
en fréquence et des diagrammes polaires

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IEC 60263 ®
Edition 4.0 2020-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Scales and sizes for plotting frequency characteristics and polar diagrams

Échelles et dimensions des graphiques pour le tracé des courbes de réponse

en fréquence et des diagrammes polaires

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.140.50 ISBN 978-2-8322-8497-1

– 2 – IEC 60263:2020 © IEC 2020
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Characteristics plotted versus a logarithmic frequency scale . 6
4.1 Decibel vs. log frequency plots . 6
4.2 Log quantities vs. log frequency plots . 7
5 Polar level diagrams . 7
5.1 General . 7
5.2 Polar plots of absolute level . 7
5.3 Polar plots of relative level . 7
Annex A (informative) Examples of the requirements specified in this document . 8
Annex B (informative) Information regarding linear y-axis vs. logarithmic frequency
plots . 14
B.1 General . 14
B.2 Phase . 14
B.3 Group delay . 14

Figure A.1 – Example of a microphone calibration curve showing the relative response
in dB as a function of frequency with an aspect ratio of 10 dB/decade . 8
Figure A.2 – Example of the response of a loudspeaker crossover filter network with
an aspect ratio of 20 dB/decade . 9
Figure A.3 – Example of the response of a loudspeaker with an aspect ratio of

25 dB/decade (dB re. 20 µPa) . 9
Figure A.4 – Example of the response of a hearing aid with an aspect ratio of
50 dB/decade. 10
Figure A.5 – Example of the noise from a mobile communications device with an
aspect ratio of 0,5 decades/decade (10 dB/decade) . 10
Figure A.6 – Example of amplifier noise with an aspect ratio of 1 decade/decade

(20 dB/decade) . 11
Figure A.7 – Example of total harmonic distortion of an earphone with an aspect ratio
of 1,25 decades/decade (25 dB/decade) . 11
Figure A.8 – Example of total harmonic distortion of a loudspeaker with an aspect
ratio of 2,5 decades/decade (50 dB/decade) . 12
Figure A.9 – Example of a polar diagram of absolute level with a range of 60 dB,

showing the sound pressure level from a siren at a distance of 3 m . 12
Figure A.10 – Example of a polar diagram of relative level with a range of 30 dB and a
reference circle radius of 25 dB, showing the directional response of a highly
directional shotgun microphone at 2,5 kHz . 13

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SCALES AND SIZES FOR PLOTTING FREQUENCY
CHARACTERISTICS AND POLAR DIAGRAMS

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60263 has been prepared by IEC technical committee TC 29:
Electroacoustics.
This fourth edition cancels and replaces the third edition published in 1982. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) the scope is expanded to include electronic files (e.g., PDF), scientific publications, graphs
in other standards, and screen displays in programs and apps;
b) a Terms and Definitions clause has been added;
c) aspect ratios of 20 dB/decade, and 0,5, 1, 1,25, and 2,5 decades/decade have been added;
d) ranges of 60 dB or 30 dB are specified for polar plots of absolute level; a 30 dB range is
specified for polar plots of relative level;
e) as most graphs are now computer generated, tolerances and sizes have been removed;
f) all informative figures have been updated with contemporary examples;

– 4 – IEC 60263:2020 © IEC 2020
g) an informative annex with information about linear y-axis vs. logarithmic frequency has been
added.
The text of this International Standard is based on the following documents:
CDV Report on voting
29/1038/CDV 29/1060/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.
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.

INTRODUCTION
Historically, on analogue level recorders, 1 dB was represented by 1 mm, 2 mm or 5 mm,
corresponding to level ranges of 50 dB, 25 dB and 10 dB, respectively. One of these three level
ranges was equal in length to 1 decade on the logarithmic frequency scale of the paper used
for the plot, limiting the available aspect ratios. With the advent of computer-generated
graphics, plots can now be of any size that is legible or enlarged on a display as necessary.
A plot of the data may only represent a graphical summary that is convenient for communicating
via a report or other publication where one does not wish to list out the entire data set. This
further emphasizes the importance of the visual representation.
Therefore, in order to gain an accurate impression from a graph in which a response is plotted
as level (in decibels) or as an amplitude or percentage on a logarithmic y-axis versus frequency
on a logarithmic scale, it remains important that the aspect ratio be standardized. Otherwise, a
spectrum or response curve can be made to appear unduly flat or unduly steep by compression
or expansion of one of the axes.
The subject of interest is usually a frequency response or output spectrum that results from the
application of an input spectrum to a device such as a microphone, amplifier, hearing aid,
headphone, or loudspeaker, or alternatively, level differences for the response of these devices
compared to a reference response. Analogous characteristics may be measured and plotted for
the mechanical vibration of structures. Similarly, an insertion gain or transmission loss may be
plotted. For cascaded systems, the contribution of each sub-system to the overall result is more
readily understood if each characteristic is plotted to a standard aspect ratio.
For displaying frequency spectra and response characteristics, different ranges are often
needed. A range of 10 dB may suffice for the response of a standard measurement microphone,
but a range of more than 60 dB may be required for a filter or loudspeaker. Although these
requirements illustrate the need for different aspect ratios, the number of standard aspect ratios
should be kept to a minimum to facilitate comparisons.
Graphs for publication may be reduced or enlarged to fit the printed page. Likewise, graphs
may appear on the display of a computer screen or mobile app. Therefore, the use of a standard
aspect ratio makes it feasible to compare graphs from different sources or to view the same
data displayed on different sized displays.

– 6 – IEC 60263:2020 © IEC 2020
SCALES AND SIZES FOR PLOTTING FREQUENCY
CHARACTERISTICS AND POLAR DIAGRAMS

1 Scope
This document specifies standard aspect ratios for logarithmic or level characteristics
expressed in decibels versus a logarithmic frequency axis and ranges for the radius of polar
diagrams of level. Applications include hard copy printouts, electronic files (e.g., PDF files),
scientific publications, screen displays in computer programs and apps, as well as graphs in
standards.
Informative examples of graphs that conform to the requirements in this document are found in
Annex A.
Although outside the scope of this document, graphs with a linear y-axis versus logarithmic
frequency (e.g., phase, group delay, etc.) often accompany the standard aspect ratio graphs of
level described in the normative part of this document. These are described in informative
Annex B.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
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:
• ISO Online browsing platform: available at https://www.iso.org/obp
• IEC Electropedia: available at http://www.electropedia.org/
3.1
aspect ratio
scale proportion between the y-axis and x-axis of a graph
Note 1 to entry: For graphs with a logarithmic frequency x-axis, the aspect ratio is expressed as the y-axis factor
per decade (in frequency), for example 25 dB/decade, or 1,25 decades/decade.
3.2
decade
factor of 10 on a logarithmic scale
Note 1 to entry: For example, 500 Hz is 1 decade above 50 Hz; 0,01 % is 3 decades below 10 %.
4 Characteristics plotted versus a logarithmic frequency scale
4.1 Decibel vs. log frequency plots
For graphs in which the y-axis depicts a level (in decibels) plotted versus logarithmic frequency
on the x-axis, the aspect ratio shall be 10 dB/decade, 20 dB/decade, 25 dB/decade or
50 dB/decade.
NOTE Direct comparison of hardcopy printouts to older analogue plots is facilitated by ensuring that 1 dB is equal
to 1 mm, 2 mm, or 5 mm, as required.
4.2 Log quantities vs. log frequency plots
For graphs in which the y-axis depicts an absolute quantity or a percentage on a logarithmic
amplitude scale plotted versus logarithmic frequency on the x-axis, the aspect ratio shall be
0,5 decades/decade, 1 decade/decade, 1,25 decades/decade or 2,5 decades/decade.
NOTE These aspect ratios correspond exactly to the level equivalents of 10 dB/decade, 20 dB/decade,
25 dB/decade and 50 dB/decade in 4.1, respectively.
5 Polar level diagrams
5.1 General
Polar level diagrams shall depict level as increasing outward versus radius. The angle of
incidence shall be depicted as increasing moving counterclockwise relative to the reference
direction. The angle assigned to the reference direction shall be 0°. Major angular divisions
shall be plotted as radii at a minimum of 30° intervals and shall be labelled.
5.2 Polar plots of absolute level
For a polar plot of absolute level referred to a reference quantity (e.g. dB re. 20µPa), the level
range of the graph shall be 60 dB or 30 dB to the origin.
For polar plots of absolute level with a range of 60 dB to the origin, the maximum level shall be
plotted less than 10 dB below the circle of maximum radius. Major level divisions shall be plotted
as concentric circles with radii in multiples of 10 dB. Major divisions shall be labelled. Optional
minor divisions are plotted as circles in 2 dB intervals without labels.
For polar plots of absolute level with a range of 30 dB to the origin, the maximum level shall be
plotted less than 5 dB below the circle of maximum radius. Major level divisions shall be plotted
as circles with radii in multiples of 5 dB. Major divisions shall be labelled. Optional minor
divisions are plotted as circles in 1 dB intervals without labels.
5.3 Polar plots of relative level
For a polar plot of relative level, such as the difference between the absolute level from a
transducer and the absolute level in a reference direction, the level range of the graph shall be
30 dB to the origin. The reference circle shall represent a relative level of 0 dB. The reference
circle radius shall be 10 dB, 15 dB, or 20 dB or 25 dB. The maximum level shall be plotted less
than or equal to 5 dB below the circle of maximum radius. Major level divisions shall be plotted
as circles with radii in multiples of 5 dB. Major divisions shall be labelled. Optional minor
divisions are plotted as circles in 1 dB intervals without labels.
NOTE The level in the reference direction is 0 dB.

– 8 – IEC 60263:2020 © IEC 2020
Annex A
(informative)
Examples of the requirements specified in this document
Examples of plots with the eight aspect ratios specified in this document are shown in
Figure A.1 through Figure A.8, respectively. The examples are plotted with typical data but are
not intended to restrict the plotting of data to any one of the aspect ratios or ranges illustrated.
Figure A.8 also shows the equivalence of level difference in decibels and percentage on a
logarithmic amplitude scale with a secondary y-axis scale in decibels on the right-hand side.
NOTE Minor gridlines following a base-10 pattern are preferred.
Figure A.9 is an example of a polar diagram according to this document with a 60 dB range,
showing the sound pressure level emitted by a siren at a distance of 3 m.
Figure A.10 is an example of a polar diagram showing the directional response of a shotgun
highly directional microphone at 2,5 kHz, relative to its on-axis response. The range of the plot
is 30 dB and the reference circle radius is a level difference of 25 dB.

Figure A.1 – Example of a microphone calibration curve showing the relative response
in dB as a function of frequency with an aspect ratio of 10 dB/decade

Figure A.2 – Example of the response of a loudspeaker crossover filter
network with an aspect ratio of 20 dB/decade

Figure A.3 – Example of the response of a loudspeaker
with an aspect ratio of 25 dB/decade (dB re. 20 µPa)

– 10 – IEC 60263:2020 © IEC 2020

Figure A.4 – Example of the response of a hearing aid
with an aspect ratio of 50 dB/decade

Figure A.5 – Example of the noise from a mobile communications device
with an aspect ratio of 0,5 decades/decade (10 dB/decade)

Figure A.6 – Example of amplifier noise with an aspect ratio of
1 decade/decade (20 dB/decade)

Figure A.7 – Example of total harmonic distortion of an earphone
with an aspect ratio of 1,25 decades/decade (25 dB/decade)

– 12 – IEC 60263:2020 © IEC 2020

Figure A.8 – Example of total harmonic distortion of a loudspeaker
with an aspect ratio of 2,5 decades/decade (50 dB/decade)

Figure A.9 – Example of a polar diagram of absolute level with a range of 60 dB,
showing the sound pressure level from a siren at a distance of 3 m

Figure A.10 – Example of a polar diagram of relative level with a range of 30 dB
and a reference circle radius of 25 dB, showing the directional response of
a highly directional shotgun microphone at 2,5 kHz

– 14 – IEC 60263:2020 © IEC 2020
Annex B
(informative)
Information regarding linear y-axis vs. logarithmic frequency plots
B.1 General
Graphs with a linear y-axis versus logarithmic frequency, such as phase, group delay, etc.,
often accompany the standard aspect ratio graphs of level described in the normative part of
this document. These graphs are, in general, subject to many of the same issues with respect
to comparison. Therefore, some guidelines are given to facilit
...