SIST EN ISO 3743-2:2009
(Main)Acoustics - Determination of sound power levels of noise sources using sound pressure - Engineering methods for small, movable sources in reverberant fields - Part 2: Methods for special reverberation test rooms (ISO 3743-2:1994)
Acoustics - Determination of sound power levels of noise sources using sound pressure - Engineering methods for small, movable sources in reverberant fields - Part 2: Methods for special reverberation test rooms (ISO 3743-2:1994)
This part of IS0 3743 specifies a relatively simple engineering method for determining the sound power levels of small, movable noise sources. The measurements are carried out when the source is installed in a specially designed room having a specified reverberation time over the frequency range of interest. The A-weighted sound power level of the source under test is determined from a single Aweighted sound pressure level measurement at each microphone position, rather than from a summation of octave-band levels. This direct method eliminates the need for a reference sound source, but requires the use of a special reverberation test room. The direct method is based on the premise that the sound pressure level, averaged in space and time in the test room, can be used to determine the sound power level emitted by the source. The properties of the special reverberation test room are chosen so that the room's influence on the sound power output of the equipment under test is small. The number of microphone positions and source locations required in the test room are specified. Guidelines for the design of special reverberation rooms are given in annex B.
Akustik - Bestimmung der Schalleistungspegel von Geräuschquellen aus Schalldruckmessungen - Verfahren der Genauigkeitsklasse 2 für kleine, transportable Quellen in Hallfeldern - Teil 2: Verfahren für Sonder-Hallräume (ISO 3743-2:1994)
Acoustique - Détermination des niveaux de puissance acoustique émis par les sources de bruit à partir de la pression acoustique - Méthodes d'expertise en champ réverbéré applicables aux petites sources transportables - Partie 2: Méthodes en salle d'essai réverbérante spéciale (ISO 3743-2:1994)
IEC 60358-4:2018 s'applique aux diviseurs capacitifs monophasés pour courant alternatif ou pour courant continu connectés entre la ligne et la terre utilisés pour la fabrication de transformateurs de tension ainsi que pour d'autres applications.
IEC 60358-4:2018 doit être utilisées conjointement avec IEC 60358-1:2012. IEC 60358-4:2018 a été établie sur la base de IEC 60358-1:2012. IEC 60358 complètent ou modifient les articles correspondants de l'IEC 60358-1:2012.
Akustika - Ugotavljanje ravni zvočnih moči virov hrupa z merjenjem zvočnega tlaka - Inženirske metode za majhne premične vire v odmevnih poljih - 2. del: Metode za posebne odmevnice (ISO 3743-2:1994)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 3743-2:2009
01-november-2009
1DGRPHãþD
SIST EN ISO 3743-2:1997
$NXVWLND8JRWDYOMDQMHUDYQL]YRþQLKPRþLYLURYKUXSD]PHUMHQMHP]YRþQHJD
WODND,QåHQLUVNHPHWRGH]DPDMKQHSUHPLþQHYLUHYRGPHYQLKSROMLKGHO
0HWRGH]DSRVHEQHRGPHYQLFH ,62
Acoustics - Determination of sound power levels of noise sources using sound pressure -
Engineering methods for small, movable sources in reverberant fields - Part 2: Methods
for special reverberation test rooms (ISO 3743-2:1994)
Akustik - Bestimmung der Schalleistungspegel von Geräuschquellen aus
Schalldruckmessungen - Verfahren der Genauigkeitsklasse 2 für kleine, transportable
Quellen in Hallfeldern - Teil 2: Verfahren für Sonder-Hallräume (ISO 3743-2:1994)
Acoustique - Détermination des niveaux de puissance acoustique émis par les sources
de bruit à partir de la pression acoustique - Méthodes d'expertise en champ réverbéré
applicables aux petites sources transportables - Partie 2: Méthodes en salle d'essai
réverbérante spéciale (ISO 3743-2:1994)
Ta slovenski standard je istoveten z: EN ISO 3743-2:2009
ICS:
17.140.01 $NXVWLþQDPHUMHQMDLQ Acoustic measurements and
EODåHQMHKUXSDQDVSORãQR noise abatement in general
SIST EN ISO 3743-2:2009 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 3743-2:2009
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SIST EN ISO 3743-2:2009
EUROPEAN STANDARD
EN ISO 3743-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2009
ICS 17.140.01 Supersedes EN ISO 3743-2:1996
English Version
Acoustics - Determination of sound power levels of noise
sources using sound pressure - Engineering methods for small,
movable sources in reverberant fields - Part 2: Methods for
special reverberation test rooms (ISO 3743-2:1994)
Acoustique - Détermination des niveaux de puissance Akustik - Bestimmung der Schalleistungspegel von
acoustique émis par les sources de bruit à partir de la Geräuschquellen aus Schalldruckmessungen - Verfahren
pression acoustique - Méthodes d'expertise en champ der Genauigkeitsklasse 2 für kleine, transportable Quellen
réverbéré applicables aux petites sources transportables - in Hallfeldern - Teil 2: Verfahren für Sonder-Hallräume (ISO
Partie 2: Méthodes en salle d'essai réverbérante spéciale 3743-2:1994)
(ISO 3743-2:1994)
This European Standard was approved by CEN on 13 July 2009.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2009 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 3743-2:2009: E
worldwide for CEN national Members.
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SIST EN ISO 3743-2:2009
EN ISO 3743-2:2009 (E)
Contents Page
Foreword .3
Annex ZA (informative) Relationship between this European Standard and the Essential
Requirements of EU Directive 98/37/EC .4
Annex ZB (informative) Relationship between this European Standard and the Essential
Requirements of EU Directive 2006/42/EC .5
2
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SIST EN ISO 3743-2:2009
EN ISO 3743-2:2009 (E)
Foreword
The text of ISO 3743-2:1994 has been prepared by Technical Committee ISO/TC 43 “Acoustics” of the
International Organization for Standardization (ISO) and has been taken over as EN ISO 3743-2:2009 by
Technical Committee CEN/TC 211 “Acoustics” the secretariat of which is held by DS.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by January 2010, and conflicting national standards shall be withdrawn at
the latest by January 2010.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 3743-2:1996.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association, and supports essential requirements of EC Directives.
For relationship with EC Directives, see informative Annexes ZA and ZB, which are integral parts of this
document.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 3743-2:1994 has been approved by CEN as a EN ISO 3743-2:2009 without any modification.
3
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SIST EN ISO 3743-2:2009
EN ISO 3743-2:2009 (E)
Annex ZA
(informative)
Relationship between this European Standard and the Essential
Requirements of EU Directive 98/37/EC
This European Standard has been prepared under a mandate given to CEN by the European Commission
and the European Free Trade Association to provide a means of conforming to Essential Requirements of the
New Approach Directive 98/37/EC, amended by 98/79/EC on machinery.
Once this standard is cited in the Official Journal of the European Communities under that Directive and has
been implemented as a national standard in at least one Member State, compliance with the normative
clauses of this standard confers, within the limits of the scope of this standard, a presumption of conformity
with the relevant Essential Requirements of that Directive and associated EFTA regulations.
WARNING - Other requirements and other EU Directives may be applicable to the product(s) falling within the
scope of this standard.
4
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SIST EN ISO 3743-2:2009
EN ISO 3743-2:2009 (E)
Annex ZB
(informative)
Relationship between this European Standard and the Essential
Requirements of EU Directive 2006/42/EC
This European Standard has been prepared under a mandate given to CEN by the European Commission
and the European Free Trade Association to provide a means of conforming to Essential Requirements of the
New Approach Directive 2006/42/EC on machinery.
Once this standard is cited in the Official Journal of the European Communities under that Directive and has
been implemented as a national standard in at least one Member State, compliance with the normative
clauses of this standard confers, within the limits of the scope of this standard, a presumption of conformity
with the relevant Essential Requirements of that Directive and associated EFTA regulations.
WARNING — Other requirements and other EU Directives may be applicable to the product(s) falling within
the scope of this standard.
5
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SIST EN ISO 3743-2:2009
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SIST EN ISO 3743-2:2009
INTERNATIONAL
ISO
STANDARD
3743-2
First edition
1994-11-01
Acoustics - Determination of Sound
power levels of noise sources using Sound
- Engineering methods for
pressure
small, -movable sources in reverberant
fields -
Part 2:
Methods for special reverberation test rooms
Acoustique - Determination des niveaux de puissance acoustique 6mis
par les sources de bruit ~9 partir de Ia Pression acoustique - Methodes
d ’expertise en champ r&erb&6 applicables aux petites sources
transportables -
Partie 2: Methodes en salle d ’essai rkverbkan te spkciale
Reference number
ISO 37432:1994(E)
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SIST EN ISO 3743-2:2009
ISO 3743-2: 1994(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. Esch member body interested in a subject for
which a technical committee has been established has the right to be re-
presented 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
(1 EC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard ISO 3743-2 was prepared by Technical Committee
lSO/TC 43, Acoustics, Subcommittee SC 1, Noise.
This first edition cancels and replaces the ISO 3743:1988, of which it
constitutes a minor revision.
ISO 3743 consists of the following Parts, under the general title
Acoustics - Determination of Sound power levels of noise sources using
Sound pressure - Engineering methods for small, movable sources in
reverberan t fields:
- Part 7: Comparison method for hard-walled test rooms
- Part 2: Methods for special reverberation test rooms
Annex A forms an integral patt of this part of ISO 3743. Annexes B, C and
D are for information only.
0 ISO 1994
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronie or mechanical, including photocopying and
microfilm, without Permission in writing from the publisher.
International Organization for Standardization
Gase Postale 56 l CH-l 211 Geneve 20 l Switzerland
Printed in Switzerland
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SIST EN ISO 3743-2:2009
0 ISO
ISO 3743-2: 1994(E)
0.1 ISO 3743 is one of the ISO 3740 series, which specifies various
methods for determining the Sound power Ievels of machines, equipment
and sub-assemblies. These basic Standards specify the acoustical re-
quirements for measurements appropriate for different test environments
as shown in table 0.1. When selecting one of the methods of the ISO 3740
series, it is necessary to select the most appropriate for the conditions and
purposes of the noise test. General guidelines to assist in the selection
are provided in ISO 3740. The ISO 3740 series gives only general prin-
ciples regarding the operating and mounting conditions of the machine or
equipment under test. Reference should be made to the noise test code
for a specific type of machine or equipment, if available, for specifications
on mounting and operating conditions.
0.2 The method given in this part of ISO 3743 enables measurement
of Sound pressure levels with A-weighting and in octave bands at pre-
scribed fixed microphone positions or along prescribed paths. lt allows
determination of A-weighted Sound power levels or Sound power levels
with other weighting and octave-band Sound power levels. Quantities
which cannot be determined are the directivity characteristics of the
Source and the temporal Pattern of noise radiated by sources emitting
non-steady noise.
0.3 Parts 1 and 2 of ISO 3743 specify engineering methods for deter-
mining the A-weighted and octave-band Sound power levels of small noise
sources. The methods are applicable to small machines, devices, com-
ponents and sub-assemblies which tan be installed in a special reverber-
ation test room or in a hard-walled test room with prescribed acoustical
characteristics. The methods are particularly suitable for small items of
portable equipment; they are not intended for larger pieces of stationary
equipment which, due to their manner of Operation or installation, cannot
readily be moved into the test room and operated as in normal usage. The
procedures are intended to be used when an engineering grade of accu-
racy is desired without requiring the use of laboratoty facilities.
0.4 In ISO 3743-1, a comparison method is used to determine the
octave-band Sound power levels of the Source. The spatial average
(octave-band) Sound pressure Ievels produced by the Source under test
are compared to the spatial average (octave-band) Sound pressure levels
produced by a reference Sound Source of known Sound power output. The
differente in Sound pressure levels is equal to the differente in Sound
power levels if conditions are the Same for both sets of measurements.
The A-weighted Sound power level is then calculated from the octave-
band Sound power levels.
. . .
Ill
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SIST EN ISO 3743-2:2009
ISO 3743-2: 1994( lg 0 ISO
The requirements to be fulfilled by the special reverberation test room for
measurements in accordance with this part of ISO 3743 are significantly
more restrictive than those placed on the hard-walled test room by the
comparison method of ISO 3743-1.
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SIST EN ISO 3743-2:2009
International
Classification of Sound power levels Optional information
Test environment Volume of Source Character of noise
Standard methodl) available
obtainable
Steady, broad-band
Reverberation room
Precision In one-third-octave A-weighted Sound
Steady, discrete fre-
meeting specified
(grade 1) or octave bands power ievel
quency or narrow-
requirements
Preferably less than
band
1 % of test room
Hard-walled test
volume
Steady, broad-band,
room
Engineering Other weighted Sound
A-weighted and in
narrow-band, or dis-
(grade 2) octave bands power ievels
Special reverber-
trete frequency
ation test room
Engineering Outdoors or in large Greatest dimension
Directivity information
AnY
(grade 2) room less than 15 m
A-weighted and in and Sound pressure
one-third-octave or leveis as a function of
Preferably less than
Precision Anechoic or semi-
time; other weighted
octave bands
3745 0,5 % of test room
AnY
(grade 1) anechoic room
Sound power levels
volume
Sound pressure levels
No restrictions: limi-
No special test en- as a function of time;
3746 Survey (grade 3) ted only by available A-weighted
AnY
vironment other weighted Sound
test environment
power levels
No special test en-
Steady, broad-band,
vironment; Source
Sound power levels in
3747 Survey (grade 3) No restrictions narrow-band, or dis- A-weighted
under test not mov- octave bands
trete frequency
able
1) See ISO 2204.
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SIST EN ISO 3743-2:2009
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SIST EN ISO 3743-2:2009
INTERNATIONAL STANDARD 0 ISO ISO 3743=2:1994(E)
- Determination of Sound power levels of
Acoustics
noise sources using Sound pressure - Engineering
methods for small, movable sources in reverberant
fields -
Part 2:
Methods for special reverberation test rooms
the requirements on the test room for the comparison
1 Scope
method of ISO 3743-1 are considerably less restric-
tive, it is recommended that the comparison method
1.1 General
of ISO 3743-1 be used if a special reverberation test
room is not available.
This patt of ISO 3743 specifies a relatively simple en-
gineering method for determining the Sound power
NOTE 1 Precision methods for the determination of the
levels of small, movable noise sources. The
Sound power levels of small noise sources are specified in
ISO 3741 and ISO 3745.
measurements are carried out when the Source is in-
stalled in a specially designed room having a specified
reverberation time over the frequency range of
interest. The A-weighted Sound power level of the 1.2 Types of noise
Source under test is determined from a Single A-
The methods specified in this part of ISO 3743 are
weighted Sound pressure level measurement at each
suitable for measurements of all types of noise within
microphone Position, rather than from a summation
a specified frequency range, except impulsive noise
of octave-band Ievels. This direct method eliminates
consisting of isolated bursts of Sound energy.
the need for a reference Sound Source, but requires
the use of a special reverberation test room. The di-
NOTES
rect method is based on the premise that the Sound
pressure level, averaged in space and time in the test
2 A classification of different types of noise is given in
room, tan be used to determine the Sound power
ISO 12001.
level emitted by the Source. The properties of the
special reverberation test room are Chosen so that the 3 For sources of impulsive noise consisting of short-
duration noise bursts, the free-field methods specified in
room ’s influence on the Sound power output of the
ISO 3744 and ISO 3745 should be used.
equipment under test is small. The number of micro-
phone positions and Source locations required in the
test room are specified. Guidelines for the design of
1.3 Noise Source
special reverberation rooms are given in annex B.
On addition to the direct method, a comparison The noise Source may be a device, machine, com-
ponent or sub-assembly.
method is also described (see 8.3). However, since
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SIST EN ISO 3743-2:2009
0 ISO
ISO 3743-2: 1994(E)
The maximum size of the Source under test and the confidence that it lies within the range + 1,960, of
-
lower limit of the frequency range for which the the measured value. For further examples, reference
may be made to the ISO 9296 and ISO 7574 series.
methods are applicable depend upon the size of the
room used for the acoustical measurements. The
volume of the noise sources should not exceed 1 %
of the volume of the special reverberation test room.
For the minimum test room volume of 70 m3, the re-
NOTES
commended maximum size of the Source is 0,7 m3.
4 The Standard deviations listed in table 1 are associated
Measurements on sources emitting discrete-
with the test conditions and procedures defined in this part
frequency components below 200 Hz are frequently
of ISO 3743, and not with the noise Source itself. They arise
difficult to make in such small rooms.
partly from variations between measurement laboratories in
the geometry of the test room, the acoustical properties of
the test room boundaries, background noise, the type and
calibration of instrumentation, and the reference Sound
1.4 Measurement uncettainty
Source. They are also due to variations in experimental
measurement techniques, including microphone placement
Determinations made in accordance with this patt of
and spatial averaging, location of Source under test, inte-
ISO 3743 result, with few exceptions, in Standard
gration times, and measurement of reverberation time.
deviations of reproducibility equal to or less than
5 If several laboratories use similar facilities and instru-
2,0 dB from 500 Hz to 4 000 Hz, 3,0 dB for 250 Hz
mentation, the results of Sound power determinations on a
and 8 000 Hz, and 5,0 dB for 125 Hz (see table 1).
given Source in those laboratories may be in better agree-
ment than would be implied by the Standard deviations
A Single value of the Sound power level of a noise
given in table 1.
Source determined according to the procedures of
this part of ISO 3743 is likely to differ from the true
6 For a particular family of Sound sources, of similar size
value by an amount within the range of the measure-
with similar Sound power spectra and similar operating
ment uncertainty. The uncertainty in determinations
conditions, the Standard deviations of reproducibility may
of the Sound power level arises from several factors
be smaller than the values given in table 1. l-lence, a noise
which affect the results, some associated with en- test code for a particular type of machinery or equipment
making reference to this part of ISO 3743 may state stan-
vironmental conditions in the measurement laboratory
dard deviations smaller than those listed in table 1 if sub-
and others with experimental techniques.
stantiation is available from the results of suitable
interlaboratory tests.
If a particular noise Source were to be transported to
each of a number of different laboratories, and if, at
7 The Standard deviations of reproducibility, as tabulated
each laboratory, the Sound power level of that Source
in table 1, include the uncertainty associated with repeated
were to be determined in accordance with this patt
measurements on the same noise Source under the same
of ISO 3743, the results would show a scatter. The
conditions (for Standard deviation of repeatability, see
Standard deviation of the measured levels could be
ISO 7574-1). This uncertainty is usually much smaller than
calculated (see examples in ISO 7574-4: 1985, the uncertainty associated with interlaboratory variability.
However, if it is difficult to maintain stable operating or
annex B) and would vary with frequency. With few
mounting conditions for a particular Source, the Standard
exceptions, these Standard deviations would not ex-
deviation of repeatability may not be small compared with
ceed those listed in table 1. The values given in
the values given in table 1. In such cases, the fact that it
table 1 are Standard deviations of reproducibility, aR,
was difficult to obtain repeatable Sound power level data on
as defined in ISO 7574-1. The values of table 1 take
the Source should be recorded and stated in the test report.
into account the cumulative effects of measurement
uncertainty in applying the procedures of this part of
8 The procedures of this part of ISO 3743 and the stan-
ISO 3743, but exclude variations in the Sound power
dard deviations given in table 1 are applicable to measure-
ments on an individual machine. Characterization of the
output caused by changes in operating conditions
Sound power levels of batches of machines of the same
(e.g. rotational Speed, line voltage) or mounting con-
family or type involves the use of random sampling tech-
ditions.
niques in which confidence intervals are specified, and the
results are expressed in terms of statistical upper limits. In
The measurement uncertainty depends on the stan-
applying these techniques, the total Standard deviation must
dard deviation of reproducibility tabulated in table 1
be known or estimated, including the Standard deviation of
and on the degree of confidence that is desired. As
production, as defined in ISO 7574-1, which is a measure
examples, for a normal distribution of Sound power
of the Variation in Sound power output between individual
levels, there is a 90 % confidence that the true value
machines within the batch. Statistical methods for the
of the Sound power level of a Source lies within the
characterization of batches of machines are described in
range + 1,645~~ of the measured value and a 95 %
ISO 7574-4.
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SIST EN ISO 3743-2:2009
0 ISO
ISO 3743-2: 1994(E)
ISO 7574-4:1985, Acoustics - Statistical methods for
determining and verifying sta ted noise emission val-
Table 1 - Estimated values of the Standard
ues of machinery and equipment - Part 4: Methods
deviation of reproducibility of Sound power levels
for stated values for batches of machines.
determined according to this part of ISO 3743
Octave-band centre Standard deviation of
I EC 225: 1966, Octave, half-octave and third-octave
frequency reproducibility, aR
band filters intended for the analysis of Sounds and
Hz dB
vibra tions.
125
510
IEC 651 :1979, Sound level meters.
250
3,O
I EC 804: 1985, Integrating-averaging Sound level
500to4 000
28
me ters.
8 000
3,O
I EC 942: 1988, Sound calibrators.
2 0')
A-weighted l
1) Applicable to a Source which emits noise with a
3 Definitions
relatively “flat” spectrum in the frequency range
100 Hz to IO 000 Hz.
For the purposes of this part of ISO 3743, the defi-
nitions given in ISO 3743-1 and the following defi-
nition apply.
2 Normative references
3.1 special reverberation test room: A test room
meeting the requirements of this patt of ISO 3743.
The following Standards contain provisions which,
through reference in this text, constitute provisions
4 Requirements for special
of this part of ISO 3743. At the time of publication, the
editions indicated were valid. All Standards are subject
reverberation test room
to revision, and Parties to agreements based on this
part of ISO 3743 are encouraged to investigate the
4.1 General
possibility of applying the most recent editions of the
Standards indicated below. Members of IEC and ISO
Guidelines for the design of a suitable test room and
maintain registers of currently valid International
an example of the determination of the nominal re-
Standards.
Verberation time of the room are given in annex B.
Methods of measurement of reverberation time are
ISO 3741:1988, Acoustics - Determination of Sound
given in ISO 354.
power levels of noise sources - Precision methods
for broad-band sources in reverbera tion rooms.
4.2 Volume of test room
ISO 3743-1:1994, Acoustics - Determination of
The volume of the test room shall be at least 70 m3
Sound power levels of noise sources - Engineering
and preferably greater if the 125 Hz octave band is
methods for small, movable sources in reverberant
within the frequency range of interest. If the 4 kHz
fields - Part 1: Comparison me thod for hard-walled
and 8 kHz octave bands are within the frequency
test rooms.
range of interest, the volume shall not exceed
300 m3.
ISO 3745:1977, Acoustics - Determination of Sound
power levels of noise sources - Precision methods
NOTE 9 When using the comparison method, the use of
for anechoic and semi-anechoic rooms.
larger room volumes is acceptable.
ISO 6926:1990, Acoustics - Determination of Sound
power levels of noise sources - Requirements for 43 . Reverberation time of test room
the Performance and calibration of reference Sound
The calculation of Sound power levels from measured
sources.
values of the Sound pressure levels requires a com-
ISO 7574-1: 1985, Acoustics - Statistical methods for pensation for the frequency-dependent concentration
determining and verifying sta ted noise emission val- of Sound energy near the Walls of the test room. To
ues of machinery and equipment - Part 1: General facilitate this compensation, the reverberation time
considera tions and definitions. should be slightly higher at low frequencies. The re-
3
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SIST EN ISO 3743-2:2009
0 ISO
ISO 3743-2: 1994(E)
Source has absorptive surfaces, the reverberation
Verberation time T of the test room shall fall within the
time T shall be measured with these items present.
limiting curves defined by T = 0,9 R Tnom and
where the reverberation Parameter, R, is
IJ R T ”,,,
given by
4.4 Surface treatment
R = 1 + 257/(f V ’j3)
The floor of the test room shall be reflective with an
where
absorption coefficient less than 0,06. Except for the
floor, none of the surfaces shall have absorptive
f is the frequency, in hertz;
properties significantly deviating from each other. For
each octave band within the frequency range of in-
V is the volume, in cubic metres.
terest, the mean value of the absorption coefficient
of each wall and of the ceiling shall be within 0,5 and
For frequencies above 6,3 kHz, constants 0,9 and IJ
1,5 times the mean value of the absorption coefficient
shall be replaced by 0,8 and 1,2, respectively. The
of the Walls and ceiling.
nominal reverberation time of the room, Tnom, is de-
termined by centring the measured values of T (nor-
malized to the reverberation time at 1 000 Hz) within
4.5 Criterion for background noise
the limiting curves specified above, and shall be be-
tween 0,5 s and 1,0 s (see annex B for an example).
At each microphone Position, the Sound pressure
For a room volume V of 70 m3, the value of R is de-
Ievels due to background noise shall be at least 4 dß
termined from figure 1.
and preferably more than IO dB below the A-
weighted Sound pressure Ievel or the band pressure
If, during the acoustical measurements, sound-
absorptive structures support the Source or if the levels produced by the Source.
2
18
I
1 I4
e
-
&
G 12 &
...
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