Acoustics - Determination of sound insulation performance of cabins - Laboratory and in situ measurements (ISO 11957:1996)

Describes a laboratory method and in situ methods for the determination of the sound insulation performance of sound-protecting cabins. Applicable to sound-protecting cabins with a leak ratio smaller than 2 %.

Akustik - Messung der Schalldämmung von Schallschutzkabinen - Messungen im Labor und im Einsatzfall (ISO 11957:1996)

Diese Internationale Norm legt Verfahren zur Messung der Schalldämmung von Schallschutzkabinen im Labor (Abschnitt 6) und im Einsatzfall (Abschnitt 7) fest. Die Schalldämmung ist die von der Kabine bewirkte Minderung des Schalldruck- oder Schalleistungspegels. Die Verfahren sind auf Schallschutzkabinen mit geringem Öffnungsanteil (  2 %) anwendbar.
Diese Internationale Norm gilt nur für eine vollständige Schallschutzkabine und nicht für die einzelnen Bauteile, aus denen sie hergestellt wurde.
ANMERKUNG 1   Die Schalldämmungen für Kabinenteile, wie z. B. Wandelemente, Türen, Fenster, Schalldämpfer, sollten nach anderen diesbezüglichen Normen gemessen werden.
Die Anforderungen an die Messumgebung im Labor basieren auf denjenigen, die in ISO 3741 festgelegt sind.

Acoustique - Détermination des performances d'isolation acoustique des cabines - Mesurages en laboratoire et in situ (ISO 11957:1996)

La présente Norme internationale décrit une méthode de laboratoire (article 6) et des méthodes in situ (article 7) pour la détermination des performances d'isolation acoustique des cabines de protection phonique. La performance d'isolation acoustique est la réduction du niveau de pression acoustique ou du niveau de puissance acoustique occasionné par la cabine. Les méthodes sont applicables à des cabines à faible taux de fuite (θ < 2 %). La présente Norme internationale s'applique exclusivement à une cabine complète et non aux composants individuels qui la constituent.  
NOTE 1 L'isolement acoustique des composants de la cabine, tels que les éléments de cloison, les portes, les fenêtres, les silencieux, etc., devrait être mesuré suivant les normes adéquates. Les exigences concernant l'environnement d'essai en laboratoire sont basées sur celles figurant dans l'ISO 3741.

Akustika - Ugotavljanje zvočnoizolacijskih lastnosti kabin - Merjenje v laboratoriju in na terenu (ISO 11957:1996)

General Information

Status
Published
Publication Date
18-Aug-2009
Technical Committee
Drafting Committee
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
19-Aug-2009
Completion Date
19-Aug-2009

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SLOVENSKI STANDARD
SIST EN ISO 11957:2009
01-november-2009
1DGRPHãþD
SIST EN ISO 11957:1999

$NXVWLND8JRWDYOMDQMH]YRþQRL]RODFLMVNLKODVWQRVWLNDELQ0HUMHQMHYODERUDWRULMX

LQQDWHUHQX ,62

Acoustics - Determination of sound insulation performance of cabins - Laboratory and in

situ measurements (ISO 11957:1996)
Akustik - Messung der Schalldämmung von Schallschutzkabinen - Messungen im Labor
und im Einsatzfall (ISO 11957:1996)
Acoustique - Détermination des performances d'isolation acoustique des cabines -
Mesurages en laboratoire et in situ (ISO 11957:1996)
Ta slovenski standard je istoveten z: EN ISO 11957:2009
ICS:
17.140.01 $NXVWLþQDPHUMHQMDLQ Acoustic measurements and
EODåHQMHKUXSDQDVSORãQR noise abatement in general
SIST EN ISO 11957:2009 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN ISO 11957:2009
---------------------- Page: 2 ----------------------
SIST EN ISO 11957:2009
EUROPEAN STANDARD
EN ISO 11957
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2009
ICS 17.140.01 Supersedes EN ISO 11957:1996
English Version
Acoustics - Determination of sound insulation performance of
cabins - Laboratory and in situ measurements (ISO 11957:1996)

Acoustique - Détermination des performances d'isolation Akustik - Messung der Schalldämmung von

acoustique des cabines - Mesurages en laboratoire et in Schallschutzkabinen - Messungen im Labor und im

situ (ISO 11957:1996) Einsatzfall (ISO 11957:1996)
This European Standard was approved by CEN on 3 August 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 11957:2009: E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN ISO 11957:2009
EN ISO 11957:2009 (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

---------------------- Page: 4 ----------------------
SIST EN ISO 11957:2009
EN ISO 11957:2009 (E)
Foreword

The text of ISO 11957:1996 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 11957:2009 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 11957:1996.

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 11957:1996 has been approved by CEN as a EN ISO 11957:2009 without any modification.

---------------------- Page: 5 ----------------------
SIST EN ISO 11957:2009
EN ISO 11957:2009 (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.
---------------------- Page: 6 ----------------------
SIST EN ISO 11957:2009
EN ISO 11957:2009 (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.
---------------------- Page: 7 ----------------------
SIST EN ISO 11957:2009
---------------------- Page: 8 ----------------------
SIST EN ISO 11957:2009
INTERNATIONAL
IS0
STANDARD
11957
First edition
1996-l 2-01
Acoustics - Determination of sound
insulation performance of cabins -
Laboratory and in situ measurements
Acoustique - Dgtermina tion des performances d ’isola tion acoustique des
cabines - Mesurages en laboratoire et in situ
Reference number
IS0 11957: 1996(E)
---------------------- Page: 9 ----------------------
SIST EN ISO 11957:2009
IS0 11957: 1996(E)
Contents Paae

1 Scope ............................................................................................ 1

2 Normative references .................................................................... 1

3 Definitions ...................................................................................... 1

4 Test environment and choice of suitable quantity ......................... 2
..............................................................................
5 Instrumentation 3
6 Measurement of sound insulation performance in the laboratory . . 3

6.1 General ................................................................................. 3

6.2 Cabin location ....................................................................... 3

6.3 Cabin mounting and conditions ............................................ 3
6.4 Measurement of the sound pressure level in the room.. ...... 4
6.5 Measurement of the sound pressure level inside the cabin

6.6 Sound pressure insulation, Dp .............................................. 4

6.7 Measurement of noise inside the cabin due to noise
sources forming an integral part of the cabin (internal

noise level, L& ....................................................................

7 Measurement of sound insulation performance in situ.. ................

7.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7.2

External sound field ,.............................................................

7.3 Cabin mounting and conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

74 . Microphone positions in the room . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7s . Microphone positions inside the cabin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.6 Apparent sound pressure insulation, D>
77 .
Measurement of noise inside the cabin due to noise
sources forming an integral part of the cabin (internal

noise level, &A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

0 IS0 1996

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced

or utilized in any form or by any means, electronic or mechanical, including photocopying and

microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
---------------------- Page: 10 ----------------------
SIST EN ISO 11957:2009
@ IS0 IS0 11957: 1996(E)

8 Weighted sound pressure insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

9 Estimated cabin noise insulation for a specific noise spectrum..... 7

10 Uncertainty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

11 Information to be recorded

11 .I Test object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

11.2 Test conditions . . . . . . . . . . . . . . ..~.................................................... 8

11.3 Instrumentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

11.4 Acoustical data . . . ..*............................................................... 8

11.5 Further information . . . . . . . . . . . . . . . . . . . . . . . . ..*.................................... 8

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

12 Information to be reported
Annexes
A Estimated cabin noise insulation for a specific noise spectrum.....

B Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

. . .
III
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SIST EN ISO 11957:2009
IS0 11957: 1996(E) @ IS0
Foreword
IS0 (the International Organization for Standardization) is a worldwide fed-
eration of national standards bodies (IS0 member bodies). The work of
preparing International Standards is normally carried out through IS0
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 lialison with ISO, also take part in the work. IS0 collabo-
rates closely with the International Electrotechnical Commission (IEC) on
all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are cir-
culated 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 IS0 11957 was prepared by Technical Committee
ISO/lC 43, Acoustics, Subcommittee SC 1, Noise, on request from
CEN/TC 211, Acoustics.
Related standards concern noise attenuation measurements of enclosures
under laboratory conditions (IS0 11546-l) and in situ (IS0 11546-2).
Annexes A and B of this International Standard are for information only.
---------------------- Page: 12 ----------------------
SIST EN ISO 11957:2009
INTERNATIONAL STANDARD @ IS0
IS0 11957:1996(E)
Acoustics - Determination of sound insulation performance of
cabins - Laboratory and in situ measurements
IS0 717-I :-
’ ), Acoustics - Rating of sound insu-
1 Scope
lation in buildings and of building elements - Part I:
This International Standard specifies a laboratory Airborne sound insulation.
method (clause 6) and in situ methods (clause 7) for
IS0 3741: -*), Acoustics - Determination of sound
the determination of the sound insulation performance
power levels of noise sources using sound press-
of sound-protecting cabins. The sound insulation per-
ure - Precision methods for reverberation rooms.
formance is the reduction in sound pressure level or
sound power level afforded by the cabin. The methods
IS0 4871 :I 996, Acoustics - Declaration and verifi-
are applicable to cabins with a small leak ratio
cation of noise emission values of machinery and
(e s 2 %).
equipment.
This International Standard is applicable to a complete
IEC 651 :I 979, Sound /eve/ meters.
cabin only and not to the individual components from
which it is made.
I EC 804: 1985, Integrating-averaging sound level
meters.
NOTE 1 Sound insulations for cabin components such as
wall elements, doors, windows, silencers, etc. should be
I EC 942: 1988, Sound calibrators.
measured according to other relevant standards.
I EC 1260: 1995, E lectroacoustics - Octave-band and
Requirements for the test environment in the labora-
fractional-octave-band filters.
tory are based on those given in IS0 3741.
2 Normative references
3 Definitions
The following standards contain provisions which,
For the purposes of this International Standard, the
through reference in this text, constitute provisions of
following definitions apply.
this International Standard. At the time of publication,
the editions indicated were valid. All standards are
subject to revision, and parties to agreements based
3.1 A-weighting: Frequency weighting in accord-
on this International Standard are encouraged to in-
ance with IEC 651.
vestigate the possibility of applying the most recent
editions of the standards indicated below. Members of

IEC and IS0 maintain registers of currently valid lnter- 3.2 cabin: An enclosure specially designed to shield

national Standards. human beings from environmental noise.
1) To be published. (Revision of IS0 717-I : 1982)
2) To be published. (Revision of IS0 3741: 1988 and IS0 3742:1988)
---------------------- Page: 13 ----------------------
SIST EN ISO 11957:2009
IS0 11957: 1996(E) @ IS0

3.3 sound pressure level, Lp: Ten times the log- sound pressure insulation, D>. (See note 2 and

arithm to the base 10 of the ratio of the mean-square clause 8.)
sound pressure to the square of the reference sound
pressure (= 20 PPa). It is expressed in decibels.
3.10 estimated cabin noise insulation, DpA g
Calculated reduction in A-weighted sound pressu ’re
level for a specific spectrum (the actual noise), ob-
34 . average sound pressure level (on a mean-
tained from Dp measured in accordance with this
square basis), L, :
International Standard. It is expressed in decibels.
(See annex A.)
1 oQ1 LPI+ l()W LP2+ ,.. + 1p LPn
3.11 apparent estimated cabin noise insulation,
Lp =lOlg dB
Calculated reduction in A-weighted sound
D>A &
pressure level for a specific spectrum (the actual
noise), obtained from D> measured in accordance
with this International Standard. It is expressed in
are the sound pressure levels,
‘--Y Lp
decibels. (See note 2 and annex A.)
in decibels, to be averaged;
n is the number of values to be
3.12 internal noise level, Lp~: A-weighted average
averaged.
sound pressure level inside the cabin caused by
sound sources which are an integrated part of the
It is expressed in decibels.
cabin. It is expressed in decibels.
3.5 sound pressure insulation, Dp: Difference, in
3.13 background noise level: Averaged sound
one-third-octave or octave bands, between the sound
pressure level inside or outside the cabin when the
pressure level of an external reverberant sound field
loudspeakers, the actual environmental noise and
and the sound pressure level inside a cabin located in
the sound sources which are an integrated part of the
this field. It is expressed in decibels.
cabin are switched off. It is expressed in decibels.
3.6 apparent sound pressure insulation, D$ Dif-
3.14 leak ratio, 8: Ratio between the area of all
ference, in one-third-octave or octave bands, between
openings of the cabin and the total interior surface
the sound pressure level in a room and the sound
area (including openings) of the cabin.
pressure level in a cabin located in the room. It is ex-
NOTES
pressed in decibels. The sound field in the room need
not necessarily be diffuse.
3 The reciprocal value of the leak ratio is designated the
seal ratio, w(w= l/e>.
NOTE 2 The word “apparent” indicates that the measure-
ment has been carried out under in situ conditions.
4 Openings provid ed with sufficiently effecti silencers
opening
are not regarded as s in this context.
3.7 apparent A-weighted sound pressure insu-
lation, DlpA: Difference in A-weighted sound pressure
3.15 empty cabin: Normally equipped cabin with no
levels measured in the room and in the cabin, respec-
human beings inside.
tively, when the actual environmental noise is used as
the sound source. It is expressed in decibels. (See
3.16 reverberant sound field: That portion of the
note 2.)
sound field in the test room where the influence of
sound received directly from the source is negligible.
3.8 weighted sound pressure insulation, Dpw:
Single-number value determined in accordance with
3.17 room: Enclosed space, external to the cabin,
the method stated in IS0 717-1. It is expressed in
where sound is generated.
decibels. However, the sound reduction index used in
IS0 717-1 is replaced by the sound pressure insula-
tion, Dp. (See clause 8.)
4 Test environment and choice
of suitable quantity
3.9 apparent weighted sound pressure insula-
tion, D&,: Single-number value determined in ac-
If the test is conducted in a laboratory (clause 6), the
cordance’ with the method stated in IS0 717-1. It is
test environment shall be a reverberation room as
expressed in decibels. However, the sound reduction
specified in IS0 3741. If the test is conducted in situ
index used in IS0 717-1 is replaced by the apparent
---------------------- Page: 14 ----------------------
SIST EN ISO 11957:2009
@ IS0
IS0 11957:1996(E)
8 For measurements carried out in situ, class 2 instru-
(clause 7), no specific requirements concerning the
ments are acceptable.
room need be fulfilled. An external sound field gener-
ated in the room is used to determine the cabin sound
pressure insulation.
Differences can occur between laboratory and in situ
6 Measurement of sound insulation
test results. Therefore, only data based on the same
performance in the laboratory
measurement method shall be used when comparing
the performance of different cabins.
6.1 General
NOTE 5 The size and volume of the cabin may influence

the sound insulation performance. Consequently, it is rec- The test environment shall be a reverberation room

ommended that only data for cabins of approximately equal complying with the specifications given in IS0 3741.

sizes be used when comparing the performance of different
cabins.
A reverberant sound field is generated in the room and
the sound pressure level difference between the room
In cases where a single-number value is wanted as a
and the inside of an empty cabin is determined. (See
general quantity describing the sound insulation, the
6.4 to 6.6.)
weighted sound pressure insulation, D!, w, is the pre-
ferred quantity. The weighted sound tiressure insu-
lation is a practical single-number value to be used for
6.2 Cabin locations
a rough comparison of different cabins. However, this
quantity shall not be taken as a general measure of
The cabin shall be placed asymmetrically on the floor
the sound insulation performance of the cabin, as the
in such a way that no cabin wall is parallel to any wall
performance in actual situations strongly depends on
of the room.
the spectrum of the actual noise.
For measurements in the frequency range from
It is possible to calculate approximately the reduction
100 Hz to 10 000 Hz, the distance between the cabin
in the A-weighted sound pressure level due to the
and the walls and ceiling of the room shall be at least
cabin, using a known spectrum of the environmental
one-half wavelength corresponding to the centre fre-
noise (the actual noise). (See annex A.)
quency of the lowest frequency band of interest.
Furthermore, the distance between the cabin and any
diffusing elements in the room shall be at least one-
half of this wavelength. For measurements in the fre-
quency range from 50 Hz to 80 Hz, the distance shall
5 Instrumentation
be at least 2 m.
The cabin shall be present during all measurements in
The instrumentation system, including microphone and
cable, shall meet the requirements for a type 1 instru- the room.
ment as specified in IEC 651 or, in the case of integrat-
ing-averaging sound level meters, the requirements
for a type 1 instrument as specified in IEC 804.
6.3 Cabin mounting and conditions
NOTE 6 Generally, an integrating-averaging sound level
The cabin shall be installed as specified by the manu-
meter is preferred.
facturer.
For measurements in octave or one-third-octave
The cabin shall be empty during the measurements.
bands, the instrumentation system shall meet the re-
Unless otherwise specified in the operating instruc-
quirements for a class 1 filter as specified in IEC 1260.
tions for the cabin, the doors and windows shall be
closed, noise sources forming an integral part of the
Before and after each series of measurements, the
cabin such as ventilating fans shall be switched off,
stability and calibration of the entire instrumentation
and valves or dampers in the ventilation system shall
shall be verified at one or more frequencies over the
be open when measuring the sound insulation per-
frequency range of interest using an acoustical calibra-
formance. For additional information, the sound insu-
tor of class 1 in accordance with IEC 942.
lation performance with the valves closed may be de-
termined. The sound pressure level inside the cabin
NOTES
due to noise sources forming an integral part of the
cabin, if any, shall be determined as specified in 6.7.
7 An equivalent verification method which has been
All movable parts of the cabin shall be operated at
proved capable of checking the stability of the measure-
ment system may be used. least 10 times before the measurement is carried out.
---------------------- Page: 15 ----------------------
SIST EN ISO 11957:2009
IS0 11957: 1996(E) @ IS0

For cabins without an integrated floor, there shall be tances between microphone positions and room sur-

faces are also valid for the distances between micro-
no leaks between the cabin and the floor of the room.
phone positions and the external surfaces of the
NOTE 9 A high degree of flanking transmission in the floor
cabin.)
of the room may influence the measurement result (sound
transmission from the room to the cabin through the floor).
The average sound pressure level over different loud-
speaker positions in the reverberation room shall be
determined as an average value on a mean-square
6.4 Measurement of the sound pressure basis.
level in the room
6.5 Measurement of the sound pressure
At least two loudspeaker positions shall be used to
level inside the cabin
generate the sound field in the reverberation room.
The measurements can be carried out either sequen-
6.51 Without a well-defined operator ’s position
tially by moving one loudspeaker cabinet between the
chosen positions, or several loudspeakers can be op-
No microphone position shall be closer to the internal
erated simultaneously provided that each loudspeaker
cabin surfaces than 0,2 d, where d is the shortest inner
has a separate noise generator and power amplifier.
dimension of the cabin. All positions shall be at least
1 m above floor level.
The distance between the loudspeaker positions shall
be at least 3 m. The distance between any loud-
The sound pressure level for each loudspeaker pos-
speaker position and the cabin shall be as great as
ition shall be measured in at least six fixed microphone
possible and at least 2 m. The distance between the
positions or by use of a rotating microphone. Fixed
loudspeakers and any microphone positions shall be
microphones shall be distributed over the entire allow-
at least 2 m.
able volume as defined above. If a rotating micro-
phone is used, the path shall cover a substantial por-
NOTE 10 The minimum distance of 2 m will be sufficient,
tion of the allowable volume.
provided that the loudspeaker is approximately omnidirec-
tional and that loudspeaker positions close to room sur-
The measured sound pressure levels in the different
faces or corners are avoided.
microphone positions shall be averaged on a mean-
square basis.
The generated sound shall be steady and have a con-
tinuous spectrum in the frequency range considered. If
the measurement is carried out using octave bands,
6.52 With a well-defined operator ’s position
the spectrum shall be approximately flat within each
For cabins with only one well-defined operator ’s pos-
octave band. The three one-third-octave band levels
ition, the averaging volume is defined by the volume
within each octave band shall not differ by more than
containing typical ear positions of an operator. If fixed
6 dB in the octave band of 125 Hz, 5 dB in the band of
microphones are used, three positions shall be dis-
250 Hz, and 4 dB in the bands of higher frequencies.
tributed on a sphere with a radius of 0,3 m and the
The output shall be sufficiently high to give a sound
centre at the head-position of the operator. If a rotating
pressure level inside the cabin exceeding the back-
microphone is used, the radius shall be 0,3 m and the
ground noise level by at least 6 dB, and preferably by
centre of the circle shall be at the head-position of the
more than 12 dB for all frequency bands of interest.
operator. The path shall be inclined by 45” relative to
Correction for the influence of background noise inside
the horizontal plane.
the cabin shall be carried out in accordance with
IS0 3741.
The measured sound pressure levels in the different
microphone positions shall be averaged on a mean-
The frequency range shall be at least 100 Hz to
square basis.
5 000 Hz for one-third-octave bands, and at least
125 Hz to 4 000 Hz for octave bands.
6.6 Sound pressure insulation, DP
NOTE 11 The preferred ranges are 50 Hz to IO 000 Hz for

one-third-octave bands, and 63 Hz to 8 000 Hz for octave The sound pressure insulation in one-third-octave or

bands.
octave bands, DP, is given by
The octave- or one-third-octave-band sound pressure . . .
Dp = (L,)room - (Lp)cabin (1)
levels in the room for each loudspeaker position
where
shall be measured in at least six fixed microphone
is the averaged sound pressure
positions distributed evenly around/above the cabin.
KJ >
p room

The procedures specified in IS0 3741:1988, clause 7, level, in decibels, in one-third-octave

or octave bands in the room;
shall be followed. (The requirements specified in
IS0 3741 :I 988, subclause 7.1.3, concerning the dis-
---------------------- Page: 16 ----------------------
SIST EN ISO 11957:2009
@ IS0 IS0 11957: 1996(E)
is the averaged sound pressure
These methods are applicable for in sifu mea
...

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