oSIST prEN ISO 3744:2023
(Main)Acoustics - Determination of sound power levels of noise sources using sound pressure - Engineering methods for an essentially free field over a reflecting plane (ISO/DIS 3744:2023)
Acoustics - Determination of sound power levels of noise sources using sound pressure - Engineering methods for an essentially free field over a reflecting plane (ISO/DIS 3744:2023)
Akustik - Bestimmung der Schallleistungs- und Schallenergiepegel von Geräuschquellen aus Schalldruckmessungen - Hüllflächenverfahren der Genauigkeitsklasse 2 für ein im Wesentlichen freies Schallfeld über einer reflektierenden Ebene (ISO/DIS 3744:2023)
Acoustique - Détermination des niveaux de puissance et d'énergie acoustiques émis par les sources de bruit à partir de la pression acoustique - Méthodes d'expertise pour des conditions approchant celles du champ libre sur plan réfléchissant (ISO/DIS 3744:2023)
Akustika - Ugotavljanje ravni zvočnih moči virov hrupa z merjenjem zvočnega tlaka - Inženirska metoda v pretežno prostem polju nad odbojno ravnino (ISO/DIS 3744:2023)
General Information
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Standards Content (Sample)
SLOVENSKI STANDARD
oSIST prEN ISO 3744:2023
01-marec-2023
Akustika - Ugotavljanje ravni zvočnih moči virov hrupa z merjenjem zvočnega
tlaka - Inženirska metoda v pretežno prostem polju nad odbojno ravnino (ISO/DIS
3744:2023)
Acoustics - Determination of sound power levels of noise sources using sound pressure -
Engineering methods for an essentially free field over a reflecting plane (ISO/DIS
3744:2023)
Akustik - Bestimmung der Schallleistungs- und Schallenergiepegel von Geräuschquellen
aus Schalldruckmessungen - Hüllflächenverfahren der Genauigkeitsklasse 2 für ein im
Wesentlichen freies Schallfeld über einer reflektierenden Ebene (ISO/DIS 3744:2023)
Acoustique - Détermination des niveaux de puissance et d'énergie acoustiques émis par
les sources de bruit à partir de la pression acoustique - Méthodes d'expertise pour des
conditions approchant celles du champ libre sur plan réfléchissant (ISO/DIS 3744:2023)
Ta slovenski standard je istoveten z: prEN ISO 3744
ICS:
17.140.01 Akustična merjenja in Acoustic measurements and
blaženje hrupa na splošno noise abatement in general
oSIST prEN ISO 3744:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN ISO 3744:2023
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oSIST prEN ISO 3744:2023
DRAFT INTERNATIONAL STANDARD
ISO/DIS 3744
ISO/TC 43/SC 1 Secretariat: DIN
Voting begins on: Voting terminates on:
2023-01-06 2023-03-31
Acoustics — Determination of sound power levels of noise
sources using sound pressure — Engineering methods for
an essentially free field over a reflecting plane
ICS: 17.140.01
This document is circulated as received from the committee secretariat.
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
ISO/CEN PARALLEL PROCESSING
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STANDARD UNTIL PUBLISHED AS SUCH.
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NATIONAL REGULATIONS.
ISO/DIS 3744:2023(E)
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PROVIDE SUPPORTING DOCUMENTATION. © ISO 2023
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oSIST prEN ISO 3744:2023
ISO/DIS 3744:2023(E)
DRAFT INTERNATIONAL STANDARD
ISO/DIS 3744
ISO/TC 43/SC 1 Secretariat: DIN
Voting begins on: Voting terminates on:
Acoustics — Determination of sound power levels of noise
sources using sound pressure — Engineering methods for
an essentially free field over a reflecting plane
ICS: 17.140.01
This document is circulated as received from the committee secretariat.
COPYRIGHT PROTECTED DOCUMENT
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© ISO 2023
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NATIONAL REGULATIONS.
Website: www.iso.org ISO/DIS 3744:2022(E)
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ii
© ISO 2023 – All rights reserved
PROVIDE SUPPORTING DOCUMENTATION. © ISO 2022
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oSIST prEN ISO 3744:2023
ISO/DIS 3744:2022(E)
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
1.1 General . 1
1.2 Types of noise and noise sources . 1
1.3 Test environment . 1
1.4 Measurement uncertainty . 1
2 Normative references . 2
3 Terms and definitions . 2
4 Test environment . 6
4.1 General . 6
4.2 Criterion for acoustic adequacy of test environment . 6
4.3 Criterion for environmental correction . 7
4.4 Criteria for background noise . 7
4.4.1 General . 7
4.4.2 Relative background noise criteria for A-weighted measurements . 8
4.4.3 Background Noise Compliance for Determination of Compliance with a
Criteria . 8
5 Instrumentation . 8
5.1 General . 8
5.2 Operational Check . 8
5.3 Verification . . 9
6 Definition, location, installation, and operation of noise source under test .9
6.1 General . 9
6.2 Auxiliary equipment . 9
6.3 Noise source location . 10
6.4 Mounting of the noise source . . 10
6.4.1 General . 10
6.4.2 Hand-held machinery and equipment . 10
6.4.3 Base-mounted, wall-mounted, and tabletop machinery and equipment . 11
6.5 Installation and mounting conditions for moving noise sources . 11
6.6 Operation of source during test . 11
7 Reference box and measurement surface .11
7.1 Reference box. 11
7.2 Measurement surface .12
7.2.1 General .12
7.2.2 Microphone orientation . 13
7.2.3 Hemispherical measurement surface . 13
7.2.4 Parallelepiped measurement surface .13
7.2.5 Cylindrical measurement surface . 14
7.2.6 Combination measurement surface . 15
8 Determination of sound power levels .15
8.1 Microphone positions on the measurement surface. 15
8.1.1 Hemispherical measurement surface . 15
8.1.2 Parallelepiped measurement surface . 16
8.1.3 Cylindrical measurement surface . 17
8.1.4 Combination measurement surface . 17
8.2 Determination of sound power levels . 17
8.2.1 Measurement of sound pressure levels . 17
8.2.2 Calculation of mean sound pressure levels . 17
8.2.3 Corrections for background noise . 18
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oSIST prEN ISO 3744:2023
ISO/DIS 3744:2022(E)
8.2.4 Calculation of surface sound pressure levels . 18
8.2.5 Calculation of sound power levels . 19
9 Measurement uncertainty .19
9.1 Methodology . 19
9.2 Typical values of σ .20
R0
9.3 Determination of σ . 20
omc
9.4 Total standard deviation σσ and expanded measurement uncertainty U .20
tot
10 Information to be recorded .21
10.1 General . 21
10.2 Noise source under test . 21
10.3 Test environment . 21
10.4 Instrumentation . 21
10.5 Acoustical data . 22
11 Test report .22
Annex A (normative) Qualification procedures for the acoustic environment and
measurement surface .23
Annex B (normative) Microphone arrays on a hemispherical measurement surface .25
Annex C (normative) Microphone arrays on a parallelepiped measurement surface .33
Annex D (normative) Microphone arrays on a cylindrical measurement surface .45
Annex E (normative) Measurement surface with segments having unequal areas .50
Annex F (normative) Alternative microphone array on a hemispherical measurement
surface for direct measurements of A-weighted sound pressure levels .51
Annex G (normative) Calculation of A-weighted sound power levels from frequency band
levels .54
Annex H (normative) Sound power levels under reference meteorological conditions .56
Annex I (normative) Laboratory Procedures for Reduction of Uncertainties Associated
with Sound Power Level Determinations .58
Annex ZA (informative) Relationship between this European Standard and the essential
requirements of Directive 2006/42/EC aimed to be covered .60
Bibliography .61
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oSIST prEN ISO 3744:2023
ISO/DIS 3744:2022(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 1, Noise.
This fourth edition of ISO 3744 constitutes a merger and a technical revision of and cancels and replaces
the third edition (ISO 3744:2010), second edition (ISO 3744:1994) and the first edition of this test
method which was issued as ISO 4872:1978.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
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oSIST prEN ISO 3744:2023
ISO/DIS 3744:2022(E)
Introduction
[2-6]
This document is one of the series ISO 3741 to ISO 3747, which specify various methods for
determining the sound power levels of noise sources including machinery, equipment and their sub-
[1]
assemblies. General guidelines to assist in the selection are provided in ISO 3740. The selection
depends on the available test environment and on the precision of the sound power level values
required. A noise test code can be established (see ISO 12001) for the individual noise source in order
to select the appropriate sound measurement surface and microphone array from among those allowed
[2] [6]
in each member of the ISO 3741 to ISO 3747 series, and to give requirements on test unit mounting,
loading and operating conditions under which the sound power levels are to be obtained. The sound
power emitted by a given source into the test environment is calculated from the mean square sound
pressure that is measured over a hypothetical measurement surface enclosing the source, and the area
of that surface.
The methods specified in this document permit the determination of the A-weighted sound power level
and optionally the sound power level in octave or 1/3-octave frequency bands.
The main body of this document defines test environment qualification criteria, testing procedures
and the associated measurement uncertainties for basic compliance with the method. Annex I
outlines additional requirements that may be applied by testing laboratories to reduce measurement
uncertainty. For applications where even greater accuracy is required, reference can be made to
[2] [13,14,15]
ISO 3745, ISO 3741 or ISO 9614. If the relevant criteria for the measurement environment
specified in this document are not met, it might be possible to refer to another standard from this
[13,14,15]
series, or to ISO 9614 .
This document describes methods of accuracy grade 2 (engineering grade) as defined in ISO 12001,
when the measurements are performed in a space that approximates an acoustically free field over a
reflecting plane. Such an environment can be found in a specially designed room, or within industrial
buildings or outdoors. Ideally, the test source should be mounted on a sound-reflecting plane located
in a large open space. For sources normally installed on the floor of machine rooms, corrections are
defined to account for undesired reflections from nearby objects, walls and ceiling, and for background
noises.
This test method was originally issued as ISO 4872 in 1978. It was first released as ISO 3744 in 1994.
A brief history of the technical requirements associated with the revisions of this test method follows.
ISO 3744:1994 required a test environment with a K ≤ 2dB in all frequency bands of interest and
2f
required measurements to be conducted in octave or one-third octave bands, with A-weighted levels
being calculated from the band level data over the frequency range of interest.
ISO 3744:2010 relaxed the requirements on the test environment to require K ≤ 4dB and allowed
2A
A-weighted levels to be determined either by calculation from frequency band level measurements or
by direct measurement using an A-weighted filter. These changes to the requirements for the test
environment and instrumentation were made to facilitate in-situ and field sound power level
determinations using equipment without proportional octave band filtering for evaluation of
compliance with regulatory requirements. Round robin studies were conducted to verify that the stated
measurement uncertainties associated with the method could be maintained using these
[26]
requirements .
In addition, the 2010 revision added methods for sound energy level determination of short duration
transient events, a number of special case sound power level determination conditions to the main
body of the standard and several new measurement parameters.
This revision of ISO 3744 removes sound energy level determination due to lack of use and because it
was highly duplicative of other text in the method. Those users with an interest in sound energy level
can continue to refer to ISO 3744:2010 until this working group develops an independent test method
on sound energy level determination. Also, this revision moves many of the special case measurement
conditions and measurement parameters into Annexes to simplify the main body of the standard to
focus on the basic sound power level determination method for typical sources and test environments.
vi
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oSIST prEN ISO 3744:2023
ISO/DIS 3744:2022(E)
In addition, a new Annex I outlines procedures that testing laboratories may apply to reduce
measurement uncertainties associated with the test method.
vii
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oSIST prEN ISO 3744:2023
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oSIST prEN ISO 3744:2023
DRAFT INTERNATIONAL STANDARD ISO/DIS 3744:2022(E)
Acoustics — Determination of sound power levels of noise
sources using sound pressure — Engineering methods for
an essentially free field over a reflecting plane
1 Scope
1.1 General
This document specifies methods for determining the sound power level of a noise source from sound
pressure levels measured on a surface enveloping the noise source (machinery or equipment) in an
environment that approximates to an acoustic free field near one or more reflecting planes. The sound
power level produced by the noise source, in frequency bands or with A-weighting applied, is calculated
using those measurements.
NOTE Differently shaped measurement surfaces can yield differing estimates of the sound power level of
a given noise source which are accounted for in the uncertainty associated with this test method, or a noise
test code that refers to this method. An appropriately drafted noise test code (see ISO 12001) gives detailed
information on the selection of the surface.
1.2 Types of noise and noise sources
The methods specified in this document are suitable for all types of noise (steady, non-steady, and
fluctuating) as defined in ISO 12001, except for short duration, impulsive events.
This document is applicable to all types and sizes of noise source (e.g. stationary or slowly moving
component or sub-assembly), provided the conditions for the measurements can be met.
NOTE It is possible that the conditions for measurements given in this document are impracticable for very
tall or very long sources such as chimneys, ducts, conveyors and multi-source industrial plants. A noise test code
for the determination of noise emission of specific sources can provide alternative methods in such cases.
1.3 Test environment
The test environments that are applicable for measurements made in accordance with this document
can be located indoors or outdoors, with one or more sound-reflecting planes present on or near which
the noise source under test is mounted. The ideal environment is a completely open space with no
bounding or reflecting surfaces other than the reflecting plane(s) (such as that provided by a qualified
hemi-anechoic chamber), but procedures are given for applying corrections (within limits that are
1)
specified) in the case of environments that are less than ideal. Annex A or ISO/DIS 26101-2:— defines
methods for determining the adequacy of the test environment and for determination of corrections to
be applied to account for the effect of the test environment.
1.4 Measurement uncertainty
Information is given on the uncertainty of the sound power levels determined in accordance with this
document, for measurements made in limited bands of frequency and with frequency A-weighting
applied. Annex I outlines procedures for testing laboratories that can be used to reduce measurement
uncertainty. The uncertainty conforms to ISO 12001, accuracy grade 2 (engineering grade). General
information on measurement uncertainty is provided in this document and additional information can
2)
be found in ISO/DIS 5114-1:— .
1) Under preparation Stage at the time of the ballot: ISO/DIS 26101-2:2022
2) Under preparation. Stage at the time of the ballot: ISO/DIS 5114-1:2022
1
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oSIST prEN ISO 3744:2023
ISO/DIS 3744:2022(E)
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.
ISO 3744:2010, Acoustics — Determination of sound power levels and sound energy levels of
...
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