IEC 62777:2016

IEC 62777 ®
Edition 1.0 2016-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Quality evaluation method for the sound field of directional loudspeaker array
systems
Méthode d'évaluation de la qualité du champ acoustique des systèmes de
haut-parleurs directionnels
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IEC 62777 ®
Edition 1.0 2016-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Quality evaluation method for the sound field of directional loudspeaker array

systems
Méthode d'évaluation de la qualité du champ acoustique des systèmes de

haut-parleurs directionnels
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.160.50 ISBN 978-2-8322-1029-8

– 2 – IEC 62777:2016  IEC 2016
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Personal acoustic zone and sound pressure level . 7
4.1 Personal acoustic zone . 7
4.2 Personal distance between listeners . 8
4.3 Personal distance between a directional loudspeaker array system and a
listener . 8
4.4 Average sound pressure level at a personal acoustic zone . 9
5 Personal acoustic zone index . 9
5.1 General . 9
5.2 PAZI-x . 10
5.3 PAZI-y . 10
5.4 PAZI-xy . 10
5.5 PAZI-xyz . 10
6 Measurement of the sound pressure level for a personal acoustic zone . 10
6.1 General . 10
6.2 Characteristics to be specified . 10
6.3 Method of measurement . 11
6.3.1 Directional loudspeaker array system . 11
6.3.2 Microphone . 11
6.3.3 Test signals . 11
6.3.4 Sound pressure level curves . 11
6.4 Test environment condition . 11
6.4.1 Temperature . 11
6.4.2 Humidity . 11
7 Indication of the characteristics to be specified . 11
Annex A (informative) Example of standard specifications for a personal audio space . 13
Bibliography . 14

Figure 1 – Personal acoustic zone . 8
Figure 2 – Personal acoustic zone and sound pressure level . 8
Figure 3 – Measuring points of the personal acoustic zone . 9

Table 1 – Characteristics to be specified . 12
Table A.1 – Personal acoustic zone – Dimensioned example . 13

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
QUALITY EVALUATION METHOD FOR THE SOUND FIELD
OF DIRECTIONAL LOUDSPEAKER ARRAY SYSTEMS

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62777 has been prepared by subcommittee subcommittee
technical area 11: Quality for audio, video and multimedia systems, of IEC technical
committee technical committee 100: Audio, video and multimedia systems and equipment.
The text of this standard is based on the following documents:
FDIS Report on voting
100/2603/FDIS 100/2637/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 4 – IEC 62777:2016  IEC 2016
The committee has decided that the contents of this publication 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.
INTRODUCTION
Directional loudspeaker array systems provide focused sound for a person to listen alone
without disturbing others. This system is convenient for consumers who want to listen to
sound without earphones or headphones.
This system would be widely used in consumer electronics, for example, smart phone or pad,
TV, computer, navigator, and game machine. The applicable area for the system could be
fitness club, exhibition room, museum, shopping mall, and etc. A simple and easy concept is
needed to evaluate the performance of the directional loudspeaker array system for a
consumer. It will provide consumers with personalized audio space criteria in order to
compare the audio sound field quality between various electronic products that have a
directional loudspeaker array system. It is important to specify the quality evaluation method
for the personal audio space and the concept of personal audio space.
This standard provides guidelines for general test methods to evaluate the quality of
directional loudspeaker array systems.

– 6 – IEC 62777:2016  IEC 2016
QUALITY EVALUATION METHOD FOR THE SOUND FIELD
OF DIRECTIONAL LOUDSPEAKER ARRAY SYSTEMS

1 Scope
This International Standard applies to directional loudspeaker array systems of any kind, and
to the parts of which they are composed or which are used as auxiliaries in such systems.
This standard deals with the determination of the performance of directional loudspeaker
array systems, the comparison of these system types, and the determination of their proper
practical application, by listing the characteristics which are useful for their specification. It
specifies uniform measurement methods for these characteristics.
This standard is restricted to a description of the audio space around a person and the
relevant method of measurement. It does not consider characteristics of loudspeakers, which
are specified in IEC 60268-5.
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 60268-1, Sound system equipment – Part 1: General
IEC 60268-2, Sound system equipment – Part 2: Explanation of general terms and
calculation methods
IEC 60268-5, Sound system equipment – Part 5: Loudspeakers
IEC 61672-1, Electroacoustics – Sound level meters – Part 1: Specifications
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
personal acoustic zone
PAZ
acoustic space occupied by a person
3.2
personal distance
distance between listeners and a directional loudspeaker array system
3.3
sound pressure level at a personal acoustic zone
P
ij
sound pressure level measured at the center of the surface j of the personal acoustic zone i

3.4
average sound pressure level at a personal acoustic zone
P
i
mean value of the sound pressure levels measured at the centers of the surfaces of the
personal acoustic zone i
3.5
personal acoustic zone index
PAZI
ratio of the average sound pressure level of the personal acoustic zone for a listener, to the
total average sound pressure levels for listeners around the directional loudspeaker array
system located at a specified personal distance
3.6
personal acoustic zone index-x
PAZI-x
ratio of the average sound pressure level of the personal acoustic zone of a listener in front of
the directional loudspeaker array system to the sum of the average sound pressure levels of
listeners at the front, the front-right, and the front-left of the system
3.7
personal acoustic zone index-y
PAZI-y
ratio of the average sound pressure level of the personal acoustic zone of a listener located in
front of the directional loudspeaker array system to the sum of the average sound pressure
levels of listeners at the front and the rear of the system
3.8
personal acoustic zone index-xy
PAZI-xy
ratio of the average sound pressure level of the personal acoustic zone of a listener located in
front of the directional loudspeaker array system to the sum of the average sound pressure
levels of listeners at the front, the front-right, the front-left and the rear of the system
3.9
personal acoustic zone index-xyz
PAZI-xyz
ratio of the average sound pressure level of the personal acoustic zone of a listener located in
front of the directional loudspeaker array system to the sum of the average sound pressure
levels of persons at the front, the front-right, the front-left, and the rear, and the front-upper,
and the front-lower of the system
4 Personal acoustic zone and sound pressure level
4.1 Personal acoustic zone
The personal acoustic zone (PAZ) is defined as an acoustic space occupied by a person as
shown in Figure 1. The dimensions of the personal acoustic zone are defined as W (width), D
(depth), and H (height). Considering the standard size of a person, the dimensions of the
personal acoustic zone shall be stated.

– 8 – IEC 62777:2016  IEC 2016
W
D
H
IEC
Figure 1 – Personal acoustic zone
4.2 Personal distance between listeners
The personal distance between separate listeners, x and z, shall be defined as the distance
between the centres of their personal acoustic zones, see Figure 2. Considering the standard
size of a person, the dimension of the personal distance between listeners shall be stated.
−x +x
P
U
P
R
P
L
P
F
+y
P
D
z
y
Directional
loudspeaker
x
array system
−y
P
B
IEC
Figure 2 – Personal acoustic zone and sound pressure level
4.3 Personal distance between a directional loudspeaker array system and a listener
The personal distance between a directional loudspeaker array system and a listener, y, shall
be defined as a distance from the centre of the directional loudspeaker array system to the
+z
−z
listener in front of the system, as shown in Figure 2. The personal distance shall be specified
by the target application area of the directional loudspeaker array system.
4.4 Average sound pressure level at a personal acoustic zone
The sound pressure level, P , shall be defined as the sound pressure level measured at the
ij
center of the surface j of the personal acoustic zone i. The average sound pressure level of
the personal acoustic zone, P , shall be the mean value of the sound pressure levels
i
measured at the center of the surfaces of the personal acoustic zone, as shown in Figure 3.
P
∑
ij
j =1
P =
i
W
D
H
IEC
Figure 3 – Measuring points of the personal acoustic zone
The average sound pressure level of the personal acoustic zone, P , at the position of listener,
i
as shown in Figure 2, is defined as follows:
a) P is the average sound pressure level of the personal acoustic zone in front of the
F
directional loudspeaker array system;
b) P is the average sound pressure level of the personal acoustic zone at the front-left of
L
the directional loudspeaker array system;
c) P is the average sound pressure level of the personal acoustic zone at the front-right of
R
the directional loudspeaker array system;
d) P is the average sound pressure level of the personal acoustic zone at the rear of the
B
directional loudspeaker array system;
e) P is the average sound pressure level of the personal acoustic zone at the front-upper of
U
the directional loudspeaker array system;
f) P is the average sound pressure level of the personal acoustic zone at the front-lower of
D
the directional loudspeaker array system.
5 Personal acoustic zone index
5.1 General
The personal acoustic zone index provides the ratio of the average sound pressure level of
the personal acoustic zone of one listener, to the average sound pressure level of another
listener at a specified personal distance.

– 10 – IEC 62777:2016  IEC 2016
5.2 PAZI-x
PAZI-x is defined as the ratio of the average sound pressure level of the personal acoustic
zone of a listener in front of the directional loudspeaker array system to the sum of the
average sound pressure levels of listeners at the front, the front-right, and the front-left of the
system. This index means a relative ratio of the average sound pressure level of the listener
in front of the directional loudspeaker array system to those of the persons who are at the left
side and right side of the listener.
PAZI-x = P /(P +P +P )
F F R L
5.3 PAZI-y
PAZI-y is the ratio of the average sound pressure level of the personal acoustic zone of a
listener located in front of the directional loudspeaker array system to the sum of the average
sound pressure levels of listeners at the front and the rear of the system. This index means a
relative ratio of the average sound pressure level of a listener in front of the directional
loudspeaker array system to that of the person who is at the rear side of the system.
PAZI-y = P /(P +P )
F F B
5.4 PAZI-xy
PAZI-xy is the ratio of the average sound pressure level of the personal acoustic zone of a
listener located in front of the directional loudspeaker array system to the sum of the average
sound pressure levels of listeners at the front, the front-right, the front-left and the rear of the
system. This index means a relative ratio of the average sound pressure level of a listener
located in front of the directional loudspeaker array system to the sum of those of the persons
who are neighboring the listener in a 2-dimensional plane, as shown in Figure 2.
PAZI-xy = P /(P +P +P +P )
F F R L B
5.5 PAZI-xyz
PAZI-xyz is the ratio of the average sound pressure level of the personal acoustic zone of a
listener located in front of the directional loudspeaker array system to the sum of the average
sound pressure levels of persons at the front, the front-right, the front-left, and the rear, and
the front-upper, and the front-lower sides of the system. This index means a relative ratio of
the average sound pressure level of a listener located in front of the directional loudspeaker
array system to the sum of the average sound pressure levels of the persons who are
neighboring the listener in 3-dimensional space.
/(P +P +P +P +P +P )
PAZI-xyz = P
F F R L B U D
6 Measurement of the sound pressure level for a personal acoustic zone
6.1 General
This standard shall be used in conjunction with IEC 60268-1, IEC 60268-2, IEC 60268-5 and
IEC 61672-1.
6.2 Characteristics to be specified
The sound pressure level shall be specified as a function of frequency measured under free
field condition at a specified constant voltage with sinusoidal signal.

6.3 Method of measurement
6.3.1 Directional loudspeaker array system
The directional loudspeaker array system shall be brought under normal measuring conditions.
6.3.2 Microphone
The measuring microphone shall be positioned in the position specified in 4.4.
6.3.3 Test signals
6.3.3.1 General
Acoustical measurements shall be made under the following measuring signal condition, and
be indicated with the results.
6.3.3.2 Sinusoidal signal
The sinusoidal test signal shall not exceed the rated voltage at any frequency. The voltage
across the input terminals of the directional loudspeaker array system under test shall be kept
constant for all frequencies unless otherwise stated.
6.3.4 Sound pressure level curves
6.3.4.1 General
One or both of the following ways may be chosen for displaying the sound pressure level
curves. A family of frequency responses to be used shall be selected for some frequencies or
frequency bands according to the application.
6.3.4.2 Curves at stated frequencies
A family of sound pressure level curves at stated frequencies shall be displayed.
6.3.4.3 Curves at stated frequency bands
A family of sound pressure level curves at stated frequency bands shall be displayed.
6.4 Test environment condition
6.4.1 Temperature
The temperature of the test room shall be a standard room temperature (23 °C ± 5 K).
6.4.2 Humidity
The humidity in the test room shall be a relative humidity (RH) of 30 % ~ 60 %.
7 Indication of the characteristics to be specified
Data that shall be given by the manufacturer are indicated in Table 1 by an “X”. Data that the
manufacturer should give are indicated by the letter “R” (recommended).
A = data that shall be specified at stated frequencies;
B = data that shall be specified at a stated frequency range.

– 12 – IEC 62777:2016  IEC 2016
This table shall be specified in a document available to buyers before purchase of the
directional loudspeaker array system.
Table 1 – Characteristics to be specified
System
Clauses and subclauses
A B
4 Personal acoustic zone and sound pressure level
4.1 Personal acoustic zone R X
4.2 Personal dista
...