SIST EN ISO 11546-2:1997

SLOVENSKI STANDARD
SIST EN ISO 11546-2:1997
01-april-1997
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Acoustics - Determination of sound insulation performances of enclosures - Part 2:
Measurements in situ (for acceptance and verification purposes) (ISO 11546-2:1995)
Akustik - Bestimmung der Schalldämmung von Schallschutzkapseln - Teil 2: Messungen
im Einsatzfall (zum Zweck der Abnahme und Nachprüfung) (ISO 11546-2:1995)
Acoustique - Détermination de l'isolement acoustique des encoffrements - Partie 2:
Mesurages sur site (aux fins d'acceptation et de vérification) (ISO 11546-2:1995)
Ta slovenski standard je istoveten z: EN ISO 11546-2:1995
ICS:
17.140.01 $NXVWLþQDPHUMHQMDLQ Acoustic measurements and
EODåHQMHKUXSDQDVSORãQR noise abatement in general
SIST EN ISO 11546-2:1997 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 11546-2:1997

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SIST EN ISO 11546-2:1997

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SIST EN ISO 11546-2:1997

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SIST EN ISO 11546-2:1997

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SIST EN ISO 11546-2:1997

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SIST EN ISO 11546-2:1997
ISO
INTERNATIONAL
STANDARD 11546-2
First edition
1995-12-15
- Determination of Sound
Acoustics
insulation performances of enclosures -
Part 2:
Measurements in sifu (for acceptance and
verification purposes)
Acoustique - Dhermination de I’isolemen t acoustique des
encoffremen ts -
Partie 2: Mesurages sur sjte (aux fins d’accepta Gon et de v&ification)
Reference number
ISO 11546-2:1995(E)

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SIST EN ISO 11546-2:1997
ISO 11546-2:1995(E)
Contents
Page
1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1 Scope
1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 Normative references . . . .
2
3 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*.*.
3
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .s.
4 Choice of measurement method
4
Instrumentation . .
5
6 Test methods applicable to enclosures with the actual Sound
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .~. 4
Source
4
6.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.2 Determination of Sound power insulation
6.3 Determination of Sound pressure insulation at a specified
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .~. . . . . . . . . . . . . . . . . . . . . . . . 5
Position
7 Test methods applicable to enclosures without the actual Sound
6
Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.2 Artificial Sound Source method
7
7.3 Weighted Sound power insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.4 Estimated noise insulation due to the enclosure for a specific
7
noise spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .~.
7
8 Uncertainty . .
Information to be recorded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .a. 7
9
................................... 7
9.1 Test Object .
7
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2 Test conditions
8
9.3 I nstrumentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.4 Acoustical data
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
9.5 Further information
IO Information to be reported . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
0 ISO 1995
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
Case Postale 56 l CH-1 211 Geneve 20 l Switzerland
Printed in Switzerland
ii

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SIST EN ISO 11546-2:1997
0 ISO
ISO 11546=2:1995(E)
Annexes
A Artificial Sound Source . . . . . . . . . . .*.
9
B Example of a Source spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
C Guidelines for evaluating the applicability of different test
environments for in situ measurements
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
D Estimated noise insulation due to the enclosure for a specific
noise spectrum
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
E Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
. . .
Ill

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SIST EN ISO 11546-2:1997
0 ISO
ISO 11546=2:1995(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
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.
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 115462 was prepared by Technical Committee
lSO/TC 43, Acoustics, Subcommittee SC 1, Noise.
ISO 11546 consists of the following Parts, under the general title Acous-
tks - Determination of Sound insulation performances of enclosures:
- Part 7: Measuremen ts under laboratory conditions (for declaration
purposes)
- Part 2: Measurements in situ (for acceptance and verification pur-
poses)
Annex A forms an integral part of this part of ISO 11546. Annexes B, C,
D and E are for information only.

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SIST EN ISO 11546-2:1997
ISO 11546=2:1995(E)
INTERNATIONAL STANDARD 0 ISO
- Determination of sound insulation
Acoustics
performances of enclosures -
Part 2:
Measurements in sifu (for acceptance and verification
purposes)
1 Scope 2 Normative references
The following Standards contain provisions which,
through reference in this text, constitute provisions
This part of ISO 11546 specifies in situ methods for
the determination of the Sound insulation perform- of this part of ISO 11546. At the time of publication,
ante (insertion loss) of machine enclosures. the editions indicated were valid. All Standards are
subject to revision, and Parties to agreements based
lt applies to a total enclosure only and not to the in- on this part of ISO 11546 are encouraged to investi-
dividual Panels from which the enclosure is made. gate the possibility of applying the most recent edi-
tions of the Standards indicated below. Members of
NOTES
IEC and ISO maintain registers of currently valid
International Standards.
1 Sound insulation for enclosure Panels such as wall el-
ements, doors, windows, silencers, etc. should be
ISO 140-6: 1978, Acoustics - Measurement of Sound
measured in accordance with other relevant Standards.
insulation in buildings and of building elemen ts -
2 Related Standards concern noise-attenuation measure- Part 6: Laboratory measurements of Impact Sound
enclosures under laboratoty conditions
ments of
insulation of floors.
(ISO 11546-1) and cabins (ISO 11957).
ISO 717-1: -l), Acoustics - Rating of Sound insu-
The measurement methods specified in this part of
lation in buildings and of building elements - Part 1:
ISO 11546 are based on International Standards in the
Airborne Sound insulation.
series ISO 3740, ISO 9614 and ISO 11200 (see
table 1). Depending on the method Chosen, the Sound
ISO 3743-1 :1994, Acoustics - Determination of
insulation Performance (insertion loss) of the enclos-
Sound power levels of noise sources - Engineering
ure is determined in terms of the reduction of Sound methods for small, movable sources in reverberant
power level or Sound pressure level. Methods are fields - Part 1: Comparison method for hard-walled
given for measurements where the enclosure sur- tes t rooms.
rounds the actual Sound Source (machine). When
these methods are not practicable, alternative ISO 374411994, Acoustics - Determination of Sound
power levels of noise sources using Sound pressure
measurements tan be performed with an artificial
- Engineering method in an essentially free field over
Sound Source. Such methods are also described in
a reflecting plane.
this part of ISO 11546.
1) To be published. (Revision of ISO 717-1:1982 and ISO 717-3:1982)

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SIST EN ISO 11546-2:1997
0 ISO
ISO 11546=2:1995(E)
ISO 3746:1995, Acoustics - Determination of Sound 3.1 A-weighting: Frequency weighting as defined
power levels of noise sources using Sound pressure in IEC 651.
- Survey method using an enveloping measurement
surface over a reflecting plane. 3.2 enclosure: A structure enveloping a noise
Source (machine), designed to protect the environ-
ISO 3747:1987, Acoustics - Determination of Sound ment from this noise Source (machine).
power levels of noise sources - Survey method us-
NOTE 3 An enclosure tan be, for example, a freestanding
ing a reference Sound Source.
structure terminated on the floor or a structure more or less
fixed to the machine. (Concerning enclosures fixed to the
ISO 4871:- *‘, Acoustics - Declara tjon and ven’fica-
machine, see clause 4.)
tion of noise emission values of machinery and
equipmen t.
3.3 Sound pressure level, L,,: Ten times the logar-
ithm to the base 10 of the ratio of the Square of the
ISO 9614-1 :1993, Acoustics - Determination of
Sound pressure of a Sound to the Square of the ref-
Sound power levels of noise sources using Sound in-
erence Sound pressure. Sound pressure levels are
Part 1: Measuremen t at discrete Points.
tensity -
expressed in decibels. The reference Sound pressure
is 20 PPa (2 x 10V5 Pa).
ISO 9614-2:-3), Acoustics - Determination of Sound
power levels of noise sources using Sound intensity
3.4 average Sound pressure level, 4: Mean-Square
- Part 2: Measurement by scanning.
of the Sound pressure levels:
ISO 11201: 1995, Acoustics - Noise emitted by ma-
OJL,l + 1 OOJL,, + . + 1 OWLi,’ dB
chinery and equipment - Measurement of emission
L,=lOlg Io
n
i 1
Sound pressure levels at a work Station and at other
specified positions - Engineering method in an es-
where Lp,, Lp2, . . . . Lpn are the Sound pressure levels,
sentially free field over a reflecting plane.
in decibels, to be averaged.
ISO 11202:1995, Acoustics - Noise emitted by ma-
3.5 Sound power level, L,: Ten times the logarithm
chinery and equipment - Measurement of emission
to the base 10 of the ratio of a given Sound power to
Sound pressure levels at a work Station and at other
the reference Sound power. lt is expressed in deci-
specified positions - Survey method in sjtu.
bels. The reference Sound power is 1 pW (1 O- l2 W).
ISO 11204: 1995, Acoustics - Noise emitted by ma-
3.6 average Sound power level, &: Mean-Square
chinery and equipment - Measurement of emission
of the Sound power levels:
Sound pressure levels at a work Station and at other
specified positions - Method requiring environ-
L,= 10 Ig i 1p-w’ + 1 oQKv2 + . + 1 OOL 1 dB
mental corrections.
n
I EC 651: 1979, Sound level meters.
are the Sound power levels, in
where kl, LU/21 .I Lw,
decibels, to be averaged.
I EC 804: 1985, In tegra ting-averaging Sound level
me ters.
3.7 Sound power insulation, D,: Reduction in
Sound power level obtained due to the enclosure
I EC 942: 1988, Sound calibrators.
(octave bands or one-third-octave bands). lt is ex-
pressed in decibels.
I EC 1 260:-4), Electroacoustics - Octave-band and
fractional-octave-band filters.
3.8 A-weighted Sound power insulation, DwA:
Reduction in the A-weighted Sound power level ob-
tained due to the enclosure for the actual Sound
Source spectrum. lt is expressed in decibels.
3 Definitions
For the purposes of this part of ISO 11546, the fol- 3.9 Sound pressure insulation, D,,: Reduction in the
lowing definitions apply. Sound pressure level at a specified Position due to the
2) To be published. (Revision of ISO 4871:1984)
3) To be published.‘
4) To be published. (Revision of IEC 225:1966)

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SIST EN ISO 11546-2:1997
Q ISO
ISO 11546=2:1995(E)
In some .specific cases, an artificial Sound Source tan
enclosure (octave bands or one-third-octave bands). It
be used instead of the Sound Source, for which the
is expressed in decibels.
enclosure is intended. This method may, for example,
3.10 A-weighted Sound pressure insulation, DPA:
be used in cases where the actual Sound Source
Reduction in A-weighted Sound pressure level at a
(machine) cannot work without auxiliary equipment
specified Position due to the enclosure for the actual
with a high noise level. Furthermore, an artificial
Sound Source spectrum. lt is expressed in decibels. Sound Source may be used in cases where it is im-
possible to achieve identical operating conditions for
3.11 estimated noise insulation due to the en-
the machine during measurements with and without
closure, DwA, or DpAe: Calculated reduction in A-
an enclosure, respectively.
weighted Sound power or Sound pressure level
obtained from D, or DP, measured in accordance with
The leak ratio of an enclosure measured in accordance
this part of ISO 11546, and a specific noise spectrum.
with this part of ISO 11546 with an artificial Sound
(See annex C.) lt is expressed in decibels.
Source should be small (0 preferably less than 2 %)
and the interior surfaces of the enclosure should be
3.12 weighted Sound power insulation, Dww:
Sound absorbing.
Single-number value determined in accordance with
the method stated in ISO 717-1 except that the Sound NOTE 7 The more the enclosure deviates from these
ideal conditions regarding leak ratio and absorption, the
reduction index is replaced by the Sound power insu-
more there is a need to take measurements using the actual
lation, D,. lt is expressed in decibels.
Sound Source.
3.13 fill ratio, 4: Ratio of the volume of the Source
In cases where a Single-number value is wanted
in an enclosure to the interior volume of that enclos-
based on measurements carried out with the artificial
ure.
Sound Source method, the weighted Sound power in-
In cases where the shape of the Source complicates
sulation, D,,, is the preferred quantity (see definition
calculation of the Source volume, the volume of a
3.12). The ‘weighted Sound power insulation is a
reference box determined in accordance with
practicable Single-number value to be used for a rough
ISO 3744 or ISO 3746 tan be used.
comparison of different enclosures. However, this
quantity must not be taken as a general measure of
3.14 leak ratio, 8: Ratio between the area of all
the Sound insulation Performance of the enclosure,
openings of the enclosure and the total interior sur-
as the Performance in actual situations strongly de-
face area of the enclosure (including openings).
pends on the spectrum of the actual noise.
NOTES
This part of ISO 11546 is intended for use together
with a relevant International Standard for the deter-
4 Openings provided with sufficiently efficient sound-
mination of Sound power level or measurement of
attenuating silencers are not regarded as openings with re-
Sound pressure level. The applicability of the different
spect to the leak ratio.
methods described is summarized in table 1 and in
5 The reciprocal value of the leak ratio is designated the
annex C.
seal ratio, Y (Y = l/@.
The requirement concerning the maximum volume of
4 Choice of measurement method the enclosure, as given by the relevant International
Standard selected from table 1, shall be fulfilled.
Accurate values of the Sound insulation Performance
of an enclosure tan only be obtained when the
If the actual noise spectrum is known or tan be as-
measurements take place with the actual Sound
sumed, the reduction in A-weighted noise level due
Source for which the enclosure is designed. Thus,
to the enclosure tan be estimated according to the
whenever practicable, methods using the real Source
method given in annex D.
shall be used. If the enclosure is fixed or otherwise
connected to the Sound Source, the Sound insulation NOTE 8 Measurement data obtained using the actual
Sound Source are not necessarily comparable with data ob-
Performance tan only be determined with the actual
tained using an artificial Sound Source. In cases where the
Sound Source.
actual Sound Source is connected to the enclosure,
structure-borne Sound may influence the measurement re-
NOTE 6 The result of an in sjtu measurement depends
sult.
on the enclosure construction and the workmanship when
installed.

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SIST EN ISO 11546-2:1997
0 ISO
ISO 11546=2:1995(E)
Table 1 - Applicability of the different test methods
International Symboll) Sub-
Test environment
Test method
Standard clause
Hard-walled test room ISO 3743-1
DW, DWA
Outdoors or in large room ISO 3744
DW, DWA
ISO 3746 D 6.1
No special test environment
WA
6.2
No special test environment ISO 3747
DWl DWA
ISO 9614-1
Actual Sound Source
No special test environment
DWl DWA
ISO 9614-2
Free-field over a reflecting plane; indoor or
ISO 11201
Dp~ DpA
outdoor
6.1
No special test environment ISO 11202 D 6.3
PA
Outdoors or in large room ISO 11204
Dpf D,,A
ISO 3743-1
Hard-walled test room
DWf Dw,,
Outdoors or in large room ISO 3744
DWf D,,,
Artificial Sound Source
test environment
1) Notation according to clause 3.
5 Instrumentation
10 An equivalent verification method which has been
proved to be capable of checking the stability of the
measurement System may be used.
The instrumentation System, including the micro-
phones and cables, shall meet the requirements for
11 For measurements carried out in accordance with
a type 1 instrument as specified in IEC 651 or, in the
ISO 3746, ISO 11202 and ISO 11204 (Survey), type 2 in-
case of integrating-averaging Sound level meters, the struments are acceptable.
requirements for a type 1 instrument as specified in
IEC 804.
6 Test methods applicable to enclosures
NOTE 9 Generally, an integrating-averaging Sound level
meter is preferred.
with the actual Sound Source
For measurements in octave or one-third-octave
bands, the instrumentation System shall meet the re-
6.1 General
quirements for a type 1 filter as specified in IEC 1260.
Before and after each series of measurements, the 6.1.1 When applying the actual Sound Source
calibration of the entire measuring System shall be method, the maximum permissible volume of the en-
verified using an acoustical calibrator with an accuracy closure is given by the relevant International Standard,
selected from table 1.
of + 0,3 dB (type 1 in accordance with IEC 942).
-
4

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SIST EN ISO 11546-2:1997
0 ISO ISO 11546=2:1995(E)
is the A-weighted Sound power level, in
6.1.2 The operating conditions of the actual Sound
LWA
decibels, measured or calculated in ac-
Source shall be representative of normal use and shall
not Change between the measurements made with cordante with the relevant International
Standard.
and without the enclosure. If a special test code ex-
ists for the actual Sound Source, the operating con-
The frequency range shall at least cover the range
ditions specified in such a test code shall be used.
100 Hz to 5 000 Hz for one-third-octave bands and
125 Hz to 4 000 Hz for octave bands.
6.1.3 If the enclosure includes active elements (e.g.
fans), these elements shall be in Operation during the
NOTE 13 Frequency ranges of 50 Hz to 10 000 Hz for
measurements. If the active elements are not in-
one-third-octave bands and 63 Hz to 8 000 Hz for octave
tended for continuous Operation, measurement shall
bands are preferred.
be carried out both with the active elements switched
on and switched off.
The A-weighted levels are calculated from the band
pressure levels when ISO 3747,
6.1.4 If practicable, choose the microphone pos- ISO 3743-1,
itions to give the same environmental corrections ISO 9614-1 and ISO 9614-2 are used. According to
both with and without the enclosure. When measur- ISO 3744, the A-weighted levels tan be calculated or
ing with the enclosure, the test Object is defined to measured directly. According to ISO 3746, only the
A-weighted Sound power level tan be determined.
be the machine with the enclosure. The microphone
positions used for measurements on the enclosed
Source shall, if practicable, be the same as those used
NOTE 14 In Order to ensure consistency between fre-
for the unenclosed Source.
quency band data and the A-weighted value, use of the
calculated A-weighted value is preferred.
NOTE 12 When measurements are carried out on en-
closures with high Sound insulation, care should be taken
to ensure that structure-borne sound/vibration in the floor
Provided that the test environments and microphone
of the test room does not influence the measurement re-
sult. positions are identical for measurements with and
without the enclosure, the Sound power Ievel differ-
ence is equal to the Sound pressure level differente
6.2 Determination of Sound power
averaged according to the Chosen International Stan-
insulation
dard. This means that under identical test conditions
(i.e. identical environmental corrections) it is not
One of the International Standards ISO 3743-1,
necessary to convert the measured Sound pressure
ISO 3744, ISO 3746, ISO 3747, ISO 9614-1 or
levels into Sound power levels before calculating the
ISO 9614-2 shall be Chosen depending on the test
level differente. If the measurements with and with-
environment.
out the enclosure cannot be carried out within a very
short period of time under fully controlled and identi-
Determine the time-averaged Sound power level dur-
cal test conditions, the Sound power levels shall be
ing a typical operational cycle of the machine.
determined.
Make the measurements with and without the en-
closure. The Sound power insulation in octave or
NOTE 15 In cases where the Sound is radiated from a
one-third-octave bands (D,) and A-weighted (&,,J are
limited part of the enclosure (e.g. from an opening) and
given by:
measurements are impeded by a high background noise
= L,(without enclosure) -
level, it is possible to determine the radiated Sound power
DW
from the enclosure on a limited area in front of the radiating
&,(with enclosure) . . .
(1) part. lt is necessary to ensure that Sound radiation from the
area of the enclosure not covered by the limited measure-
WA = &A(without enclosure) -
D
ment surface is negligible.
bA(with enclosure) . . .
(2)
where
63 Determination of Sound pressure
irLul
is the Sound power level, in decibels, in ation at a specified Position
LW
octave or one-third-octave bands
measured in accordance with the relevant Make the measurements as specified in ISO 11201,
International Standard; ISO 11202 or ISO 11204. The Sound pressure insu-
5

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SIST EN ISO 11546-2:1997
0 ISO
ISO 11546=2:1995(E)
If the enclosure includes active elements (e.g. fans),
lation in one-third-octave or octave bands (DJ and A-
an artificial Sound Source shall not be used.
weighted (DPA) are given by:
= LJwithout enclosure) -
NOTE 18 Enclosures with a small leak ratio (0 < 2 %) and
DP
with sound-absorbing interior surfaces are particularly suit-
LJwith enclosure) . . .
(3)
able for measurements with the artificial Sound Source
method.
D pA = L,,(without enclosure) -
L,,(with enclosure) . . .
(4) 7.2 Artificial Sound Source method
For measurements with precision and engineering
where
grades of accuracy, the artificial Sound Source shall
is the Sound pressure level, in decibels, in
be constructed as shown in annex A. The fill ratio
LP
one-third-octave or octave bands at a
(3.13) shall not exceed 25 %. The Sound power output
specified Position measured in accordance
shall be sufficient to give a Sound pressure level out-
with the relevant International Standard;
side the enclosure so that requirements regarding
background noise in that International Standard used
is the A-weighted Sound pressure level, in
L
PA
are fulfilled. Background noise corrections shall be
decibels, at a specified Position measured
made as indicated in that International Standard.
or calculated in accordance with the rel-
evant International Standard.
For measurements with the Survey grade of accuracy,
other types of artificial Sound sources may be applied,
Use the frequency range as given in 6.2. According to
for example loudspeakers or reference Sound sources
ISO 11201 and ISO 11204, A-weighted values tan be
(e.g. fan type). lt must, however, be realised that the
measured directly or calculated from frequency band
environment may influence the Sound power output
data. According to ISO 11202, only the A-weighted
of Sound sources with low radiation impedance and
Sound pressure level tan be measured.
thus Cause incorrect measurement results in con-
nection with insertion-loss measurements. Low-
NOTES
impedance Sound sources used for measurements on
16 For in sjtu measurements, it will often be impossible
small enclosures should be avoided.
to fulfil the requirements given in ISO 11201 concerning
test environments. If the requirements are not fulfilled, the
Note that differentes tan occur between results ob-
measurement results tan be influenced by reflected Sound.
tained from measurements carried out with different
In such cases, ISO 11202 or ISO 11204 should be applied.
types of artificial Sound sources.
17 In Order to ensure consistency between frequency
NOTES
band data and the A-weighted value, use of the calculated
A-weighted value is preferred.
19 An artificial Sound Source should be as omnidirectional
as possible. In the case of a loudspeaker, a polyhedron-type
(preferably a dodecahedron) gives an adequate approxi-
mation of uniform omnidirectional radiation.
7 Test methods applicable to enclosures
without the actual Sound Source
20 The artificial Sound Source shown in annex A has an
essentially downwards Sound radiation which implies that
the surface supporting the Sound Source will be excited
7.1 General
strongly. This should be kept in mind especially in cases
where a lightweight wooden floor is an integrated part of
Measurements carried out by use of an artificial Sound
the enclosure. The near-field influence from the Sound
Source are possible in specific cases where the actual
Source may lead to an increased Sound radiation from the
Sound Source cannot be used (see clause 4). When
other surfaces of the enclosure due to contribution of
an artificial Sound Source is used, only one-third-
structure-borne Sound from the floor.
octave or octave band insulation tan be determined
For measurements on enclosures without an integrated
directly. The A-weighted Sound insulation tan be es-
floor, there might be a risk of flanking transmission
...