Acoustics — Recommended practice for the design of low-noise workplaces containing machinery — Part 2: Noise control measures

This document deals with the technical aspects of noise control in workplaces. The various technical measures are stated, the related acoustical quantities described, the magnitude of noise reduction discussed, and the verification methods outlined. This document deals only with audible sound.

Acoustique — Pratique recommandée pour la conception de lieux de travail à bruit réduit contenant des machines — Partie 2: Moyens de maîtrise du bruit

Le présent document traite des aspects techniques de la maîtrise du bruit sur les lieux de travail. Les différents moyens techniques sont énumérés, les grandeurs acoustiques associées sont décrites, la valeur de la réduction du bruit est abordée et les méthodes de vérification sont présentées. Le présent document ne traite que des sons audibles.

General Information

Status
Published
Publication Date
02-Nov-2020
Technical Committee
Drafting Committee
Current Stage
6060 - International Standard published
Start Date
30-Oct-2020
Due Date
22-Oct-2021
Completion Date
03-Nov-2020
Ref Project

Relations

Buy Standard

Standard
ISO 11690-2:2020 - Acoustics -- Recommended practice for the design of low-noise workplaces containing machinery
English language
31 pages
sale 15% off
Preview
sale 15% off
Preview
Standard
ISO 11690-2:2020 - Acoustique -- Pratique recommandée pour la conception de lieux de travail à bruit réduit contenant des machines
French language
32 pages
sale 15% off
Preview
sale 15% off
Preview
Draft
ISO/FDIS 11690-2:Version 20-jun-2020 - Acoustics -- Recommended practice for the design of low-noise workplaces containing machinery
English language
31 pages
sale 15% off
Preview
sale 15% off
Preview

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 11690-2
Second edition
2020-10
Acoustics — Recommended practice
for the design of low-noise workplaces
containing machinery —
Part 2:
Noise control measures
Acoustique — Pratique recommandée pour la conception de lieux de
travail à bruit réduit contenant des machines —
Partie 2: Moyens de maîtrise du bruit
Reference number
ISO 11690-2:2020(E)
©
ISO 2020

---------------------- Page: 1 ----------------------
ISO 11690-2:2020(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 11690-2:2020(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Technical aspects of noise control. 1
5 Noise control at source. 3
5.1 General . 3
5.2 Noise control at source by design . 3
5.3 Information on noise emission . 4
5.4 Use of low-noise machines . 4
5.5 Modification or replacement of machine components . 7
5.6 Low noise working and production technologies . 8
5.7 Maintenance of machines and noise control devices. 8
6 Noise control on the transmission path . 8
6.1 Noise control by means of a proper spatial arrangement of the noise sources . 8
6.2 Use of noise control devices . 8
6.3 Noise control by use of sound-absorbing materials . 8
6.4 Sound propagation in structures and noise control measures .11
7 Noise control at the work station .11
8 Verification methods .12
8.1 General .12
8.2 Sound sources .12
8.3 Noise control devices.12
8.4 Workroom .12
8.5 Specified positions, work stations.12
9 New technologies .13
Annex A (informative) Modification or replacement of machine components .14
Annex B (informative) Arrangement of sound sources .16
Annex C (informative) Enclosures .17
Annex D (informative) Silencers .20
Annex E (informative) Noise barriers and screens in rooms .21
Annex F (informative) Acoustical treatment of surfaces .22
Annex G (informative) Structure-borne sound insulation .24
Annex H (informative) Airborne sound insulation of partitions .25
Annex I (informative) Noise control at the work station .26
Annex J (informative) Example of a new technology .27
Bibliography .29
© ISO 2020 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO 11690-2:2020(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
is o/ f or ewor d . ht m l .
This document was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 1, Noise,
in collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/
TC 211, Acoustics, in accordance with the Agreement on technical cooperation between ISO and CEN
(Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 11690-2:1996), of which it constitutes a
minor revision. The changes compared to the previous edition are editorial.
A list of all parts in the ISO 11690 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved

---------------------- Page: 4 ----------------------
ISO 11690-2:2020(E)

Introduction
Several standards specify methods for measurement and/or evaluation of noise. The final objective of
the ISO 11690 series is noise reduction.
A number of noise control measures are offered. However, in order to be effective, the most appropriate
noise control measure(s) should be chosen for a given situation.
It is important when non-acoustic engineers are involved in noise control practice for these engineers
to have a basic knowledge of noise emission and propagation characteristics and to understand the
basic principles of noise control.
To assist in the development of noise control in the workplace, it is essential that the information
contained in these recommended practices is disseminated through International Standards.
In order to reduce noise as a hazard in the workplace, individual countries have produced national
legislation. Generally, such national legislation requires noise control measures to be carried out in
order to achieve the lowest reasonable levels of noise emission, noise immission and noise exposure,
taking into account:
— known available measures;
— the state of the art regarding technical progress;
— the treatment of noise at source;
— appropriate planning, procurement and installation of machines and equipment.
This document, together with the two other parts in the series, outlines procedures to be considered
when dealing with noise control at workplaces, within workrooms and in the open. These recommended
practices give in relatively simple terms the basic information necessary for all parties involved in noise
control in workplaces and in the design of low-noise workplaces to promote the understanding of the
desired noise control requirements.
The purpose of the ISO 11690 series is to bridge the gap between existing literature on noise control and
the practical implementation of noise control measures. In principle, the series applies to all workplaces
and its main functions are:
— to provide simple, brief information on some aspects of noise control in workplaces;
— to act as a guide to help in the understanding of requirements in standards, directives, textbooks,
manuals, reports and other specialized technical documents;
— to provide assistance in decision making when assessing the various measures available.
The ISO 11690 series should be useful to persons such as plant personnel, health and safety officers,
engineers, managers, staff in planning and purchasing departments, architects and suppliers of plants,
machines and equipment. However, the above-mentioned parties should keep in mind that adherence
to the recommendations of the ISO 11690 series is not all that is necessary to create a safe workplace.
The effects of noise on health, well-being and human activity are many. By giving guidelines for noise
control strategies and measures, the ISO 11690 series aims at a reduction of the impact of noise on
human beings at workplaces. Assessment of the impact of noise on human beings is dealt with in other
documents.
© ISO 2020 – All rights reserved v

---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 11690-2:2020(E)
Acoustics — Recommended practice for the design of low-
noise workplaces containing machinery —
Part 2:
Noise control measures
1 Scope
This document deals with the technical aspects of noise control in workplaces. The various technical
measures are stated, the related acoustical quantities described, the magnitude of noise reduction
discussed, and the verification methods outlined.
This document deals only with audible sound.
2 Normative references
The following documents are referred to in the text in such way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 11690-1:2020, Acoustics — Recommended practice for the design of low-noise workplaces containing
machinery — Part 1: Noise control strategies
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11690-1 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Technical aspects of noise control
Noise reduction measures can be applied at source (emission), between the source and the receiver
(transmission path), and at the work station (receiver) (see Figure 1).
When dealing with the noise emission of a machine, an installation or a production process, etc., all
possible noise reduction measures should be considered (see Clause 5 and ISO 11690-1). To determine
whether noise emission is the lowest level feasible, it is necessary to consider noise emission quantities;
these are given in the noise emission declaration (see ISO 11690-1:2020, Clause 8) or determined by
measurements (carried out in compliance with the relevant standard).
An assessment of noise control devices such as enclosures, partial enclosures, barriers and screens,
silencers, etc. can be carried out by using, for example, the insertion loss data (see 6.2).
The acoustic quality of workrooms and buildings is assessed with reference to the sound insulation
regarding airborne and structure-borne sound (see 6.4), and that of workrooms with reference to
sound propagation parameters (see 6.3).
© ISO 2020 – All rights reserved 1

---------------------- Page: 6 ----------------------
ISO 11690-2:2020(E)

The overall effectiveness of noise control measures is determined from the noise immission values at
the work stations.
Generally, people located at a work station or in the vicinity of a machine are affected by the direct noise
emitted by the machine. Therefore, to reduce noise in the workplace, the most effective solution is to
reduce noise at source (primary measures). Additional measures on the transmission paths (secondary
measures) may be impractical because they hinder the work task and the production process. When
assessing the state of noise reduction technology, low noise emission of sound sources is therefore
given high priority with regard to occupational safety.
The basic aspects of noise control (see also ISO 11690-1) are illustrated in Figure 1. These are reviewed
in Clauses 5 to 7.
Figure 1 — Basic aspects of noise control
In order to minimize noise at the workplace, all noise control measures should be considered (see
Figure 2).
Figure 2 — Steps for the implementation of noise control measures
Noise control is most effective if it is carried out when planning, modifying, changing existing
machinery or equipment, or when acquiring new machinery or equipment in plants, workrooms and
buildings. From the outset, all parties involved (see ISO 11690-1:2020, Clause 6) and, in particular,
the noise experts, should take part in the process. Noise control measures are most effective if they
are integrated at the design stage of machines, production processes, workrooms and tasks (see
ISO 11690-1:2020, Clause 7). Machine operation, material transport, safety technology, ergonomics and
environmental protection should also be considered at that stage.
2 © ISO 2020 – All rights reserved

---------------------- Page: 7 ----------------------
ISO 11690-2:2020(E)

5 Noise control at source
5.1 General
The measures described in this clause deal with the reduction of noise generated by working processes
and machines. They should be implemented at the design stage because retrospective measures can
affect operational requirements and are generally more expensive. However, they are also recommended
for existing noise sources, when practicable.
Control of noise at its source in workplaces deals in particular with the noise reduction of existing
machines, the development and selection of low noise working processes and production technologies,
the replacement of machine parts and the assessment of the results obtained.
The effectiveness of noise control at its source is based on measurements and is assessed by
comparison with the noise emission data, for example, provided by the supplier/manufacturer (see
ISO 11690-1:2020, Clause 8).
5.2 Noise control at source by design
When machine noise (or noise from technical production equipment) is considered, two types of noise
generation should be distinguished: fluid dynamic noise generation (gas and/or liquid) and mechanical
generation.
Fluid dynamic noise arises from temporary fluctuations in pressure and velocity of fluids. Examples
are combustion processes, fans, blow-out openings and hydraulic systems.
Mechanically-generated noise is caused by vibrations of machine components that are excited by
dynamic forces which are generated, for example, by impacts or out-of-balance masses. The vibrations
are transmitted to noise-radiating surfaces, such as machine casing, workpieces, etc. Examples are
tooth-wheel gears, electric motors, hammers, shakers and mechanical presses (see Figure 3).
Key
1 excitation
2 machine
3 transmission
4 radiation
Figure 3 — Generation process of mechanical noise
In order to control noise at its source, the noise-generation mechanism should be taken into account.
© ISO 2020 – All rights reserved 3

---------------------- Page: 8 ----------------------
ISO 11690-2:2020(E)

Examples of reduction of fluid dynamic noise are the following:
a) reduction of periodical pressure fluctuations at the excitation source (e.g. in-line hydraulic
dampers);
b) reduction of flow velocities (e.g. speed-controlled fans);
c) avoidance of sudden changes in pressure (e.g. graduated vs abrupt transitions in HVAC ducting);
d) effective design of through-flow components (e.g. design layouts that do not put obstacles
immediately in front of air movers).
Examples of reduction of mechanically-generated noise are the following:
e) reduction of exciting dynamic forces (e.g. by means of elastic layers to extend the impulse duration
of impacts);
f) reduction of the vibrational velocity of the machine structure at the excitation point for a given
dynamic force [e.g. by means of stiffeners or additional masses (inertia blocks)];
g) reduction of the vibration (structure-borne sound) transmission from the excitation point to the
sound-radiating surfaces [e.g. by using elastic elements and materials with high internal damping
(cast iron)];
h) reduction of the sound radiated by a vibrating structure, for example by use of
— thin walls with ribs instead of thick stiff walls,
— damping layers on thin metal sheets,
— perforated metal sheets (provided noise insulation is not required);
i) sound-insulating wrappings or thick-walled structures (thin damped metal sheets near the
radiating surface).
Further information on reducing noise at its source can be found in ISO/TR 11688-1 and ISO/TR 11688-2.
5.3 Information on noise emission
In addition to the information on noise emission given by suppliers/manufacturers in technical
documentation (see ISO 11690-1:2020, Clause 8), there may be measures specific to industrial sectors.
Information on such measures can be found in databases, professional magazines, trade association
journals, etc.
For some machine families, there are lists of noise emission data obtained under specified operating
conditions. These lists can help purchasers select low-noise machines/equipment (see ISO 11690-1:2020,
Annex A).
5.4 Use of low-noise machines
In some circumstances, rather than implementing costly retrospective noise control measures, it is
feasible to replace a noisy unit in a plant with a low-noise one (see Table 1).
4 © ISO 2020 – All rights reserved

---------------------- Page: 9 ----------------------
ISO 11690-2:2020(E)

Table 1 — Examples of alternative processes with lower noise
High-noise processes Low-noise processes
Percussion riveting Compression and roll riveting
Drive by compressed air or internal combustion engine Electrical drive
Cutting or making holes in, for example, stone or con- Use of machines that can be fitted with drills or circular
crete by the use of pneumatic or internal combustion saw blades equipped with diamond teeth
percussive machines
Heading in the die Tapering/full-forward extrusion
Push cutting Pull cutting
Flow drying Radiation drying
Plasma oxygen cutting Plasma cutting under water
Cutting shock, punching Laser-beam cutting
Conventional TIG/TAG welding TIG/TAG shielded arc welding
Flame-hardening Laser-beam hardening
Fastening with rivets Pressure fixing
Stroke forming Hydraulic pressing
Spot welding Seam welding
NOTE 1 A change of the material and/or form of the component under manufacture may allow the use of low-noise
production processes.
NOTE 2 This list is by no means exhaustive.
There are also noisy operations which are not connected with fixed machines, for example from the use
of hand-held tools. These can often be the dominating noise sources in a workroom. If care is taken in
selecting the tools or the working arrangement (e.g. sound-deadened hammers, cushioned work tables,
low-noise grinding discs, magnetic damping mats, etc.), considerable noise reductions can be achieved
as shown in Figures 4 to 7.
© ISO 2020 – All rights reserved 5

---------------------- Page: 10 ----------------------
ISO 11690-2:2020(E)

Key
X octave-band frequency, in Hz
Y A-weighted sound pressure level at the work station, in dB
a
Conventional steelhammer, L = 115 dB.
pA
b
Sound-deadened hammer (with little recoil), L = 107 dB.
pA
Figure 4 — Example of sound pressure level during hammering
Key
X octave-band frequency, in Hz
Y A-weighted sound pressure level at the work station, in dB
a
Hard grinding wheel, L = 100 dB.
pA
b
Bonded abrasive grinding wheel, L = 89 dB.
pA
Figure 5 — Example of sound pressure level when grinding during the cleaning of a cast iron
electromotor housing
6 © ISO 2020 – All rights reserved

---------------------- Page: 11 ----------------------
ISO 11690-2:2020(E)

Key
Y A-weighted sound pressure level, in dB
a
Steel working plate, 25 mm thick.
b
Steel working plate, damped by viscous material, 40 mm thick.
c
Steel working plate, 200 mm thick.
Figure 6 — Example of sound pressure level when hammering
Key
X octave-band frequency, in Hz
Y A-weighted sound pressure level at the work station, in dB
a
Without magnetic mat, L = 111 dB.
pA
b
With magnetic mat, L = 102 dB.
pA
Figure 7 — Example of sound pressure level when grinding a steel plate
5.5 Modification or replacement of machine components
It is possible, by replacing or modifying machine components, to reduce noise transmission inside the
machine and noise radiation by the machine surface, without affecting performance. Annex A gives
examples of such noise reduction measures.
© ISO 2020 – All rights reserved 7

---------------------- Page: 12 ----------------------
ISO 11690-2:2020(E)

5.6 Low noise working and production technologies
It is always beneficial, if feasible, to replace a particularly noisy machine or unit in a plant with a
quieter one, for example by using a machine that works to a different principle (e.g. replacing an impact
screwdriver by a continuous direct-driven screwdriver).
With regard to existing processes, particular attention should be paid to the possibility of substituting
the process with an equally effective but quieter method.
When substituting a production process, low-noise alternatives should be systematically searched for.
The successive replacement of machines, plant items and processes by less noisy ones will in the long
term lead to quieter working environments even though low-noise machines have to be positioned
alongside existing noisy ones.
5.7 Maintenance of machines and noise control devices
Noise emission levels from machines or processes can be unnecessarily high due to lack of maintenance,
poor lubrication, misalignment, unbalanced and loose parts, etc. Optimum operating conditions should
be maintained at all times. Any maintenance defect normally increases the noise levels.
Maintenance of noise control devices is also of prime importance. Therefore, the integrity of enclosures,
screens and silencers should be carefully monitored.
6 Noise control on the transmission path
6.1 Noise control by means of a proper spatial arrangement of the noise sources
An optimized spatial arrangement of machines can provide a substantial noise level reduction at work
stations. This is mainly applicable when planning new plants and installations but should also be
considered for existing plants.
Noise reduction can be obtained by increasing the distance between the noise sources and the work
stations (see Annex B).
6.2 Use of noise control devices
Enclosures (see Annex C), silencers (see Annex D) and screens (see Annex E) can be effective measures
for the reduction of the noise emitted from machines, installations, piping systems and openings.
An enclosure is a structure completely surrounding the machine or installation. It consists mainly of
a sound-insulating shell (metal, wood, concrete, etc.) with and without an internal sound-absorbing
lining. The achievable noise reduction depends on the insulation of airborne sound provided by the
shell and on the degree of absorption by the internal surface of the enclosure if absorption exists. In
practice, it is limited by openings, ineffective seals and by transmission of structure-borne sound. This
limitation can be minimized by using measures such as silenced openings.
The effectiveness of noise control by using enclosures, silencers or screens can be measured and assessed
by the insertion loss, the transmission loss and the reduction of sound level (see ISO 11690-1:2020,
Clause 3, for definitions).
6.3 Noise control by use of sound-absorbing materials
The relationship between noise emission and noise immission is determined by sound propagation
(see ISO/TR 11690-3). Sound propagation and therefore the acoustical quality of a room are influenced
by the treatment of surfaces (ceiling and walls) by using sound-absorbing materials, which should be
selected in relation to the frequency spectrum of the noise. For attenuation of noise at low frequencies,
the use of absorptive materials is less effective.
8 © ISO 2020 – All rights reserved

---------------------- Page: 13 ----------------------
ISO 11690-2:2020(E)

Noise in rooms consists of direct noise from sources and reflected noise from room boundaries (floors,
walls, ceilings, other equipment, fittings, etc.). Absorptive surface treatment reduces exclusively the
reflected noise.
It is possible to assess the acoustical
...

NORME ISO
INTERNATIONALE 11690-2
Deuxième édition
2020-10
Acoustique — Pratique recommandée
pour la conception de lieux de
travail à bruit réduit contenant des
machines —
Partie 2:
Moyens de maîtrise du bruit
Acoustics — Recommended practice for the design of low-noise
workplaces containing machinery —
Part 2: Noise control measures
Numéro de référence
ISO 11690-2:2020(F)
©
ISO 2020

---------------------- Page: 1 ----------------------
ISO 11690-2:2020(F)

DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2020
Tous droits réservés. Sauf prescription différente ou nécessité dans le contexte de sa mise en œuvre, aucune partie de cette
publication ne peut être reproduite ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique,
y compris la photocopie, ou la diffusion sur l’internet ou sur un intranet, sans autorisation écrite préalable. Une autorisation peut
être demandée à l’ISO à l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.
ISO copyright office
Case postale 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Genève
Tél.: +41 22 749 01 11
E-mail: copyright@iso.org
Web: www.iso.org
Publié en Suisse
ii © ISO 2020 – Tous droits réservés

---------------------- Page: 2 ----------------------
ISO 11690-2:2020(F)

Sommaire Page
Avant-propos .iv
Introduction .v
1 Domaine d’application . 1
2 Références normatives . 1
3 Termes et définitions . 1
4 Aspects techniques liés à la maîtrise du bruit . 1
5 Maîtrise du bruit à sa source . 3
5.1 Généralités . 3
5.2 Maîtrise du bruit à sa source lors de la conception . 3
5.3 Informations sur l’émission de bruit . 5
5.4 Utilisation de machines à bruit réduit . 5
5.5 Modification ou remplacement de composants de machines . 7
5.6 Technologies de production et de travail à bruit réduit . 8
5.7 Maintenance des machines et des dispositifs de maîtrise du bruit . 8
6 Maîtrise du bruit sur le trajet de transmission . 8
6.1 Maîtrise du bruit par une disposition spatiale appropriée des sources de bruit . 8
6.2 Utilisation de dispositifs de maîtrise du bruit . 8
6.3 Maîtrise du bruit par l’emploi de matériaux absorbants acoustiques . 9
6.4 Propagation du son dans les structures et moyens de maîtrise du bruit .11
7 Maîtrise du bruit au poste de travail .11
8 Méthodes de vérification .12
8.1 Généralités .12
8.2 Sources sonores .12
8.3 Dispositifs de maîtrise du bruit .12
8.4 Locaux de travail.12
8.5 Positions spécifiées, postes de travail .13
9 Technologies nouvelles .13
Annexe A (informative) Modification ou remplacement de composants de machines .14
Annexe B (informative) Disposition des sources sonores .16
Annexe C (informative) Encoffrements .17
Annexe D (informative) Silencieux .20
Annexe E (informative) Barrières et écrans acoustiques à l’intérieur des locaux .21
Annexe F (informative) Traitement acoustique des parois .22
Annexe G (informative) Isolation au bruit solidien.24
Annexe H (informative) Isolation au bruit aérien par des cloisons .25
Annexe I (informative) Maîtrise du bruit au poste de travail .26
Annexe J (informative) Exemple de technologie nouvelle .27
Bibliographie .29
© ISO 2020 – Tous droits réservés iii

---------------------- Page: 3 ----------------------
ISO 11690-2:2020(F)

Avant-propos
L’ISO (Organisation internationale de normalisation) est une fédération mondiale d’organismes
nationaux de normalisation (comités membres de l’ISO). L’élaboration des Normes internationales est
en général confiée aux comités techniques de l’ISO. Chaque comité membre intéressé par une étude
a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,
gouvernementales et non gouvernementales, en liaison avec l’ISO participent également aux travaux.
L’ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui
concerne la normalisation électrotechnique.
Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont
décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier de prendre note des différents
critères d’approbation requis pour les différents types de documents ISO. Le présent document a été
rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2 (voir www
.iso .org/ directives).
L’attention est attirée sur le fait que certains des éléments du présent document peuvent faire l’objet de
droits de propriété intellectuelle ou de droits analogues. L’ISO ne saurait être tenue pour responsable
de ne pas avoir identifié de tels droits de propriété et averti de leur existence. Les détails concernant
les références aux droits de propriété intellectuelle ou autres droits analogues identifiés lors de
l’élaboration du document sont indiqués dans l’Introduction et/ou dans la liste des déclarations de
brevets reçues par l’ISO (voir www .iso .org/ brevets).
Les appellations commerciales éventuellement mentionnées dans le présent document sont données
pour information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un
engagement.
Pour une explication de la nature volontaire des normes, la signification des termes et expressions
spécifiques de l’ISO liés à l’évaluation de la conformité, ou pour toute information au sujet de l’adhésion
de l’ISO aux principes de l’Organisation mondiale du commerce (OMC) concernant les obstacles
techniques au commerce (OTC), voir le lien suivant: www .iso .org/ iso/ fr/ avant-propos.
Le présent document a été élaboré par le comité technique ISO/TC 43, Acoustique, sous-comité SC 1,
Bruit, en collaboration avec le comité technique CEN/TC 211, Acoustique, du Comité européen de
normalisation (CEN), conformément à l’Accord de coopération technique entre l’ISO et le CEN (Accord
de Vienne).
Cette deuxième édition annule et remplace la première édition (ISO 11690-2:1996), qui a fait l’objet
d’une révision mineure. Les modifications par rapport à l’édition précédente sont rédactionnelles.
Une liste de toutes les parties de la série ISO 11690 se trouve sur le site web de l’ISO.
Il convient que l’utilisateur adresse tout retour d’information ou toute question concernant le présent
document à l’organisme national de normalisation de son pays. Une liste exhaustive desdits organismes
se trouve à l’adresse www .iso .org/ fr/ members .html.
iv © ISO 2020 – Tous droits réservés

---------------------- Page: 4 ----------------------
ISO 11690-2:2020(F)

Introduction
Plusieurs normes spécifient des méthodes de mesure et/ou d’évaluation du bruit. La série ISO 11690 a
quant à elle pour objectif final la réduction du bruit.
Il existe un certain nombre de moyens de maîtrise du bruit. Néanmoins, dans un but d’efficacité, il
convient de choisir le ou les moyens de maîtrise du bruit les plus appropriés à une situation donnée.
Lorsque des ingénieurs non experts dans le domaine acoustique sont impliqués dans la pratique de la
maîtrise du bruit, il est important qu’ils disposent de connaissances de base sur les caractéristiques
d’émission et de propagation du son, et qu’ils comprennent les principes fondamentaux de la maîtrise
du bruit.
Afin de contribuer au développement de la maîtrise du bruit sur les lieux de travail, il est essentiel
que les informations contenues dans ces pratiques recommandées soient diffusées par des Normes
internationales.
Afin de diminuer les risques dus au bruit sur les lieux de travail, différents pays ont promulgué leurs
propres législations nationales. En général, ces législations exigent la mise en œuvre de moyens de
maîtrise du bruit permettant d’obtenir les niveaux d’émission sonore, de bruit ambiant et d’exposition
au bruit les plus bas possible, en tenant compte:
— des moyens techniques disponibles connus;
— de l’état actuel des progrès techniques;
— du traitement du bruit à la source;
— de la planification, de l’achat et de l’installation appropriés des machines et des équipements.
Le présent document, ainsi que les deux autres parties de cette série, présentent les procédures à
prendre en compte dans la lutte contre le bruit sur les lieux de travail, tant à l’intérieur des locaux de
travail qu’à l’air libre. Ces pratiques recommandées fournissent, dans des termes relativement simples,
les informations fondamentales nécessaires à toutes les parties concernées par la maîtrise du bruit sur
les lieux de travail et par la conception de lieux de travail à bruit réduit afin de faciliter la compréhension
des exigences souhaitées en matière de maîtrise du bruit.
L’objectif de la série ISO 11690 est de combler l’écart qui existe entre la littérature actuelle consacrée
à la maîtrise du bruit et la mise en œuvre pratique de moyens de maîtrise du bruit. En principe, cette
série s’applique à tous les lieux de travail, ses fonctions principales étant de:
— fournir des informations simples et brèves sur certains aspects de la maîtrise du bruit sur les lieux
de travail;
— tenir lieu de guide facilitant la compréhension des exigences contenues dans les normes, directives,
ouvrages de référence, manuels, rapports et autres documents techniques spécialisés;
— aider à la prise de décision lors de l’évaluation des différents moyens disponibles.
La série ISO 11690 est destinée au personnel d’usine, aux agents chargés de l’hygiène et de la sécurité, aux
ingénieurs, aux cadres dirigeants, au personnel des bureaux d’étude et services achat, aux architectes,
et aux fournisseurs d’installations, de machines et d’équipements. Cependant, il convient que les parties
concernées mentionnées ci-dessus gardent à l’esprit que la seule application des recommandations
données dans la série ISO 11690 ne suffit pas pour créer un lieu de travail sûr.
Les effets du bruit sur la santé, le bien-être et l’activité humaine sont nombreux. En fournissant un
cadre directeur pour les stratégies et les moyens de maîtrise du bruit, la série ISO 11690 a pour objectif
de réduire l’impact du bruit sur les personnes sur leur lieu de travail. L’évaluation de l’impact du bruit
sur les personnes est traitée dans d’autres documents.
© ISO 2020 – Tous droits réservés v

---------------------- Page: 5 ----------------------
NORME INTERNATIONALE ISO 11690-2:2020(F)
Acoustique — Pratique recommandée pour la conception
de lieux de travail à bruit réduit contenant des machines —
Partie 2:
Moyens de maîtrise du bruit
1 Domaine d’application
Le présent document traite des aspects techniques de la maîtrise du bruit sur les lieux de travail. Les
différents moyens techniques sont énumérés, les grandeurs acoustiques associées sont décrites, la
valeur de la réduction du bruit est abordée et les méthodes de vérification sont présentées.
Le présent document ne traite que des sons audibles.
2 Références normatives
Les documents suivants sont cités dans le texte de sorte qu’ils constituent, pour tout ou partie de leur
contenu, des exigences du présent document. Pour les références datées, seule l’édition citée s’applique.
Pour les références non datées, la dernière édition du document de référence s’applique (y compris les
éventuels amendements).
ISO 11690-1:2020, Acoustique — Pratique recommandée pour la conception de lieux de travail à bruit
réduit contenant des machines — Partie 1: Stratégies de maîtrise du bruit
3 Termes et définitions
Pour les besoins du présent document, les termes et définitions de l’ISO 11690-1 s’appliquent.
L’ISO et l’IEC tiennent à jour des bases de données terminologiques destinées à être utilisées en
normalisation, consultables aux adresses suivantes:
— ISO Online browsing platform: disponible à l’adresse https:// www .iso .org/ obp;
— IEC Electropedia: disponible à l’adresse http:// www .electropedia .org/ .
4 Aspects techniques liés à la maîtrise du bruit
Les moyens de réduction du bruit peuvent être appliqués à la source (émission), entre la source et le
récepteur (trajet de transmission) et au niveau du poste de travail (récepteur) (voir Figure 1).
Lorsque l’on traite de l’émission sonore d’une machine, d’une installation ou d’un procédé de
production, etc., il convient de considérer tous les moyens possibles de réduction du bruit (voir
Article 5 et ISO 11690-1). Pour établir si l’émission sonore est ou non au niveau le plus bas possible, il
faut considérer les grandeurs d’émission sonore; celles-ci sont fournies dans la déclaration d’émission
sonore (voir ISO 11690-1:2020, Article 8) ou déterminées par mesurages (effectués conformément à la
norme applicable).
Une évaluation des dispositifs de maîtrise du bruit tels que les encoffrements intégraux ou partiels,
les barrières et écrans, les silencieux, etc. peut être réalisée en utilisant, par exemple, les données de
pertes par insertion (voir 6.2).
© ISO 2020 – Tous droits réservés 1

---------------------- Page: 6 ----------------------
ISO 11690-2:2020(F)

La qualité acoustique des locaux de travail et des bâtiments est évaluée en se référant à l’isolation
acoustique au bruit aérien et au bruit solidien (voir 6.4), celle des locaux de travail étant également
évaluée par référence aux paramètres de propagation du son (voir 6.3).
L’efficacité globale des moyens de maîtrise du bruit est déterminée à partir des valeurs de bruit ambiant
aux postes de travail.
En règle générale, les personnes qui occupent un poste de travail d’une machine ou qui se trouvent à
proximité de celle-ci sont affectées par le bruit direct émis par la machine. Pour réduire le bruit sur les
lieux de travail, la solution la plus efficace est donc de réduire le bruit à sa source (moyens primaires).
Des moyens supplémentaires intervenant sur les trajets de transmission (moyens secondaires) peuvent
se révéler inapplicables parce qu’ils gênent l’exécution des tâches et le procédé de production. Lorsque
l’on évalue l’état de la technique en matière de réduction du bruit, une priorité élevée est donc accordée,
pour ce qui concerne la sécurité au travail, à une émission sonore faible des sources.
Les aspects fondamentaux de la maîtrise du bruit (voir également ISO 11690-1) sont illustrés à la
Figure 1. Ils sont repris dans les Articles 5 à 7.
Figure 1 — Aspects fondamentaux de la maîtrise du bruit
Pour réduire le plus possible le bruit sur les lieux de travail, il est recommandé de considérer tous les
moyens de maîtrise du bruit (voir Figure 2).
Figure 2 — Étapes de mise en œuvre des moyens de maîtrise du bruit
2 © ISO 2020 – Tous droits réservés

---------------------- Page: 7 ----------------------
ISO 11690-2:2020(F)

La maîtrise du bruit est des plus efficaces si elle est menée lors de la planification, de la modification,
du remplacement de machines ou d’équipements existants ou de l’acquisition de machines ou
d’équipements nouveaux destinés à des installations, à des locaux de travail et à des bâtiments. Dès le
départ, il convient que toutes les parties concernées (voir ISO 11690-1:2020, Article 6) et, en particulier,
les experts acousticiens, prennent part au processus. Les moyens de maîtrise du bruit sont des plus
efficaces s’ils sont intégrés au stade de la conception des machines, des procédés de production, des
locaux de travail et des tâches (voir ISO 11690-1:2020, Article 7). Il convient également de prendre en
compte à ce stade le mode de fonctionnement de la machine, le transport des matériaux, la technologie
liée à la sécurité, l’ergonomie et la protection de l’environnement.
5 Maîtrise du bruit à sa source
5.1 Généralités
Les moyens décrits dans le présent article traitent de la réduction du bruit engendré par les procédés
de travail et les machines. Il convient que ces moyens soient mis en œuvre au stade de la conception,
étant donné que des moyens rétrospectifs peuvent affecter les exigences de fonctionnement et sont
généralement plus onéreux. Toutefois, ces derniers sont également recommandés dans le cas de sources
de bruit existantes, lorsqu’il est possible de les mettre en œuvre.
La réduction du bruit à sa source, mise en œuvre sur les lieux de travail, porte en particulier sur la
réduction du bruit des machines existantes, le développement et la sélection de procédés de travail et
de technologies de production à bruit réduit, le remplacement d’éléments de machines et l’évaluation
des résultats obtenus.
L’efficacité de la maîtrise du bruit à sa source s’évalue sur la base de mesurages, par comparaison
avec les données d’émission sonore fournies, par exemple, par le fournisseur/fabricant (voir
ISO ISO 11690-1:2020, Article 8).
5.2 Maîtrise du bruit à sa source lors de la conception
En matière de bruit des machines (ou de bruit dû aux équipements techniques de production), il convient
de distinguer deux types de bruits: le bruit engendré par les fluides en mouvement (gaz et/ou liquides)
et le bruit d’origine mécanique.
Le bruit dû aux mouvements de fluides provient des fluctuations temporaires de pression et de vitesse
des fluides, notamment dans les processus de combustion, les ventilateurs, les orifices de décharge et
les systèmes hydrauliques.
Le bruit d’origine mécanique est provoqué par les vibrations de composants de machines, excités par des
forces dynamiques, elles-mêmes générées par des impacts ou des balourds, par exemple. Les vibrations
sont transmises à des surfaces sur lesquelles le bruit est rayonné, telles que carters de machine, outils,
etc. Les engrenages, les moteurs électriques, les marteaux, les vibreurs et les presses mécaniques (voir
Figure 3) en constituent quelques exemples.
© ISO 2020 – Tous droits réservés 3

---------------------- Page: 8 ----------------------
ISO 11690-2:2020(F)

Légende
1 excitation
2 machine
3 transmission
4 rayonnement
Figure 3 — Processus de génération de bruit d’origine mécanique
Pour pouvoir réduire le bruit à sa source, il convient de prendre en compte le mécanisme de génération
du bruit.
Quelques exemples de réduction du bruit dû aux mouvements de fluides sont donnés ci-après:
a) réduction des fluctuations périodiques de pression à la source d’excitation (par exemple,
amortisseurs hydrauliques en ligne);
b) réduction des vitesses d’écoulement (par exemple, ventilateurs à vitesse régulée);
c) évitement de variations brusques de pression (par exemple, transitions progressives dans les
gaines des systèmes de chauffage, ventilation et climatisation, par opposition aux transitions
soudaines);
d) conception efficace des composants placés dans l’écoulement (par exemple, conception de
configurations ne plaçant pas d’obstacles immédiatement devant des dispositifs de ventilation);
Quelques exemples de réduction du bruit d’origine mécanique sont donnés ci-après:
e) réduction des forces dynamiques d’excitation (par exemple, au moyen de couches élastiques
augmentant la durée des impacts);
f) réduction de la vitesse vibratoire de la structure mécanique au point d’excitation pour une force
dynamique donnée [par exemple, au moyen de raidisseurs ou de masses additionnelles (blocs
d’inertie)];
g) réduction de la transmission des vibrations (bruit solidien) du point d’excitation vers les surfaces
sur lesquelles le bruit est rayonné [par exemple, en utilisant des éléments et des matériaux
élastiques à amortissement interne élevé (fonte)];
h) réduction du rayonnement acoustique d’une structure vibrante, par exemple par l’utilisation:
— de parois minces nervurées en lieu et place de parois rigides et épaisses;
— de couches amortissantes sur des tôles minces;
4 © ISO 2020 – Tous droits réservés

---------------------- Page: 9 ----------------------
ISO 11690-2:2020(F)

— de tôles perforées (à condition qu’une isolation acoustique ne soit pas nécessaire);
i) utilisation d’enveloppes absorbantes acoustiques ou de structures à parois épaisses (tôles minces
amorties à proximité de la surface rayonnante).
D’autres informations sur la réduction du bruit à sa source peuvent être trouvées dans l’ISO/TR 11688-1
et l’ISO/TR 11688-2.
5.3 Informations sur l’émission de bruit
Outre les informations sur l’émission sonore fournies dans la documentation technique par les
fournisseurs/fabricants (voir ISO 11690-1:2020, Article 8), des moyens spécifiques par secteur
industriel peuvent exister. Les informations sur ces moyens peuvent être trouvées dans des bases de
données, des revues spécialisées, des publications d’associations professionnelles, etc.
Pour certaines familles de machines, il existe des listes de données d’émission sonore obtenues dans
des conditions de fonctionnement définies. Ces listes peuvent aider les acheteurs à sélectionner des
machines ou des équipements à bruit réduit (voir ISO 11690-1:2020, Annexe A).
5.4 Utilisation de machines à bruit réduit
Dans certains cas, plutôt que de mettre en œuvre des moyens de maîtrise du bruit rétrospectifs
onéreux, il est possible de remplacer un matériel bruyant dans une installation par un matériel à bruit
réduit (voir Tableau 1).
Tableau 1 — Exemples de procédés alternatifs à moindre bruit
Procédés à fort niveau de bruit Procédés à faible niveau de bruit
Rivetage par percussion Rivetage par compression et à roulement
Entraînement par air comprimé ou moteur à combus- Entraînement électrique
tion interne
Coupe ou perçage de trous dans la pierre ou le béton, par Utilisation de machines qui peuvent être munies de
exemple au moyen de machines à percussion pneumatiques forets ou de lames de scie circulaire, équipées de dents
ou à commande par combustion interne en diamant
Refoulement en matrice Extrusion par rétrécissement/à avance totale
Coupe par poussée Coupe par traction
Séchage par écoulement Séchage par rayonnement
Oxycoupage au jet de plasma Découpage au plasma sous eau
Choc de découpe, poinçonnage Découpage au laser
Soudage TIG/TAG conventionnel Soudage à l’arc protégé TIG/TAG
Durcissement à la flamme Durcissement au laser
Fixation par rivets Fixation par pression
Formage par choc Pressage hydraulique
Soudage par points Soudage à la molette
NOTE 1  Un changement de matériau et/ou de forme du composant fabriqué peut permettre l’utilisation de procédés de
production à bruit réduit.
NOTE 2  Cette liste n’a aucunement vocation à être exhaustive.
Il existe également des activités bruyantes qui ne sont pas liées à des machines fixes, comme celles qui
résultent de l’utilisation d’outils à main. Elles peuvent souvent représenter les principales sources de
bruit d’un local de travail. Si l’on sélectionne avec soin les outils ou l’agencement du poste de travail, par
exemple des marteaux insonorisés, des établis matelassés, des disques de meulage à bruit réduit, des
tapis magnétiques amortissants, etc., la réduction du bruit obtenue peut être considérable, comme le
montrent les Figures 4 à 7.
© ISO 2020 – Tous droits réservés 5

---------------------- Page: 10 ----------------------
ISO 11690-2:2020(F)

Légende
X fréquence par bandes d’octave, en Hz
Y niveau de pression acoustique pondéré A au poste de travail, en dB
a
marteau traditionnel en acier, L = 115 dB.
pA
b
marteau insonorisé (à faible rebond), L = 107 dB
pA
Figure 4 — Exemple de niveau de pression acoustique lors d’une opération de martelage
Légende
X fréquence par bandes d’octave, en Hz
Y niveau de pression acoustique pondéré A au poste de travail, en dB
a
meule dure, L = 100 dB
pA
b
meule à abrasif aggloméré, L = 89 dB
pA
Figure 5 — Exemple de niveau de pression acoustique lors d’une opération de meulage visant au
nettoyage d’un carter de moteur électrique en fonte
6 © ISO 2020 – Tous droits réservés

---------------------- Page: 11 ----------------------
ISO 11690-2:2020(F)

Légende
Y niveau de pression acoustique pondéré A, en dB
a
plaque d’acier, 25 mm d’épaisseur
b
plaque d’acier, amortie par un matériau visqueux, 40 mm d’épaisseur
c
plaque d’acier, 200 mm d’épaisseur
Figure 6 — Exemple de niveau de pression acoustique lors d’une opération de martelage
Légende
X fréquence par bandes d’octave, en Hz
Y niveau de pression acoustique pondéré A au poste de travail, en dB
a
sans tapis magnétique, L = 111 dB
pA
b
avec tapis magnétique, L = 102 dB
pA
Figure 7 — Exemple de niveau de pression acoustique lors du meulage d’une plaque d’acier
5.5 Modification ou remplacement de composants de machines
Il est possible, en remplaçant ou en modifiant des composants de machines, de diminuer la transmission
du bruit à l’intérieur des machines et le bruit rayonné par leur surface, sans nuire à leurs performances.
L’Annexe A donne des exemples de ce type de moyen de réduction du bruit.
© ISO 2020 – Tous droits réservés 7

---------------------- Page: 12 ----------------------
ISO 11690-2:2020(F)

5.6 Technologies de production et de travail à bruit réduit
Il est toujours avantageux, lorsque cela est possible, de remplacer une machine ou un élément
particulièrement bruyant d’une installation par un autre modèle plus silencieux, notamment en utilisant
une machine qui fonctionne selon un principe différent (par exemple, en remplaçant une visseuse à
percussion par une visseuse à entraînement direct continu).
Il convient d’étudier soigneusement
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 11690-2
ISO/TC 43/SC 1
Acoustics — Recommended practice
Secretariat: DIN
for the design of low-noise workplaces
Voting begins on:
2020-06-24 containing machinery —
Voting terminates on:
Part 2:
2020-09-16
Noise control measures
Acoustique — Pratique recommandée pour la conception de lieux de
travail à bruit réduit contenant des machines —
Partie 2: Moyens de réduction du bruit
ISO/CEN PARALLEL PROCESSING
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 11690-2:2020(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2020

---------------------- Page: 1 ----------------------
ISO/FDIS 11690-2:2020(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/FDIS 11690-2:2020(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Technical aspects of noise control. 1
5 Noise control at source. 3
5.1 General . 3
5.2 Noise control at source by design . 3
5.3 Information on noise emission . 4
5.4 Use of low-noise machines . 4
5.5 Modification or replacement of machine components . 7
5.6 Low noise working and production technologies . 8
5.7 Maintenance of machines and noise control devices. 8
6 Noise control on the transmission path . 8
6.1 Noise control by means of a proper spatial arrangement of the noise sources . 8
6.2 Use of noise control devices . 8
6.3 Noise control by use of sound-absorbing materials . 8
6.4 Sound propagation in structures and noise control measures .11
7 Noise control at the work station .11
8 Verification methods .12
8.1 General .12
8.2 Sound sources .12
8.3 Noise control devices.12
8.4 Workroom .12
8.5 Specified positions, work stations.12
9 New technologies .13
Annex A (informative) Modification or replacement of machine components .14
Annex B (informative) Arrangement of sound sources .16
Annex C (informative) Enclosures .17
Annex D (informative) Silencers .20
Annex E (informative) Noise barriers and screens in rooms .21
Annex F (informative) Acoustical treatment of surfaces .22
Annex G (informative) Structure-borne sound insulation .24
Annex H (informative) Airborne sound insulation of partitions .25
Annex I (informative) Noise control at the work station .26
Annex J (informative) Example of a new technology .27
Bibliography .29
© ISO 2020 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO/FDIS 11690-2:2020(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
is o/ f or ewor d . ht m l .
This document was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 1, Noise,
in collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/
TC 211, Acoustics, in accordance with the Agreement on technical cooperation between ISO and CEN
(Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 11690-2:1996), of which it constitutes a
minor revision. The changes compared to the previous edition are editorial.
A list of all parts in the ISO 11690 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved

---------------------- Page: 4 ----------------------
ISO/FDIS 11690-2:2020(E)

Introduction
Several standards specify methods for measurement and/or evaluation of noise. The final objective of
the ISO 11690 series is noise reduction.
A number of noise control measures are offered. However, in order to be effective, the most appropriate
noise control measure(s) should be chosen for a given situation.
It is important when non-acoustic engineers are involved in noise control practice for these engineers
to have a basic knowledge of noise emission and propagation characteristics and to understand the
basic principles of noise control.
To assist in the development of noise control in the workplace, it is essential that the information
contained in these recommended practices is disseminated through International Standards.
In order to reduce noise as a hazard in the workplace, individual countries have produced national
legislation. Generally, such national legislation requires noise control measures to be carried out in
order to achieve the lowest reasonable levels of noise emission, noise immission and noise exposure,
taking into account:
— known available measures;
— the state of the art regarding technical progress;
— the treatment of noise at source;
— appropriate planning, procurement and installation of machines and equipment.
This document, together with the two other parts in the series, outlines procedures to be considered
when dealing with noise control at workplaces, within workrooms and in the open. These recommended
practices give in relatively simple terms the basic information necessary for all parties involved in noise
control in workplaces and in the design of low-noise workplaces to promote the understanding of the
desired noise control requirements.
The purpose of the ISO 11690 series is to bridge the gap between existing literature on noise control and
the practical implementation of noise control measures. In principle, the series applies to all workplaces
and its main functions are:
— to provide simple, brief information on some aspects of noise control in workplaces;
— to act as a guide to help in the understanding of requirements in standards, directives, textbooks,
manuals, reports and other specialized technical documents;
— to provide assistance in decision making when assessing the various measures available.
The ISO 11690 series should be useful to persons such as plant personnel, health and safety officers,
engineers, managers, staff in planning and purchasing departments, architects and suppliers of plants,
machines and equipment. However, the above-mentioned parties should keep in mind that adherence
to the recommendations of the ISO 11690 series is not all that is necessary to create a safe workplace.
The effects of noise on health, well-being and human activity are many. By giving guidelines for noise
control strategies and measures, the ISO 11690 series aims at a reduction of the impact of noise on
human beings at workplaces. Assessment of the impact of noise on human beings is dealt with in other
documents.
© ISO 2020 – All rights reserved v

---------------------- Page: 5 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 11690-2:2020(E)
Acoustics — Recommended practice for the design of low-
noise workplaces containing machinery —
Part 2:
Noise control measures
1 Scope
This document deals with the technical aspects of noise control in workplaces. The various technical
measures are stated, the related acoustical quantities described, the magnitude of noise reduction
discussed, and the verification methods outlined.
This document deals only with audible sound.
2 Normative references
The following documents are referred to in the text in such way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
1)
ISO 11690-1:— , Acoustics — Recommended practice for the design of low-noise workplaces containing
machinery — Part 1: Noise control strategies
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11690-1 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Technical aspects of noise control
Noise reduction measures can be applied at source (emission), between the source and the receiver
(transmission path), and at the work station (receiver) (see Figure 1).
When dealing with the noise emission of a machine, an installation or a production process, etc., all
possible noise reduction measures should be considered (see Clause 5 and ISO 11690-1). To determine
whether noise emission is the lowest level feasible, it is necessary to consider noise emission quantities;
these are given in the noise emission declaration (see ISO 11690-1:—, Clause 8) or determined by
measurements (carried out in compliance with the relevant standard).
An assessment of noise control devices such as enclosures, partial enclosures, barriers and screens,
silencers, etc. can be carried out by using, for example, the insertion loss data (see 6.2).
The acoustic quality of workrooms and buildings is assessed with referee to the sound insulation
regarding airborne and structure-borne sound (see 6.4), and that of workrooms with reference to
sound propagation parameters (see 6.3).
1) Under preparation. Stage at the time of publication: ISO/FDIS 11690-1:2020 (Revision of ISO 11690-1:1996).
© ISO 2020 – All rights reserved 1

---------------------- Page: 6 ----------------------
ISO/FDIS 11690-2:2020(E)

The overall effectiveness of noise control measures is determined from the noise immission values at
the work stations.
Generally, people located at a work station or in the vicinity of a machine are affected by the direct noise
emitted by the machine. Therefore, to reduce noise in the workplace, the most effective solution is to
reduce noise at source (primary measures). Additional measures on the transmission paths (secondary
measures) may be impractical because they hinder the work task and the production process. When
assessing the state of noise reduction technology, low noise emission of sound sources is therefore
given high priority with regard to occupational safety.
The basic aspects of noise control (see also ISO 11690-1) are illustrated in Figure 1. These are reviewed
in Clauses 5 to 7.
Figure 1 — Basic aspects of noise control
In order to minimize noise at the workplace, all noise control measures should be considered a priori
(see Figure 2).
Figure 2 — Steps for the implementation of noise control measures
Noise control is most effective if it is carried out when planning, modifying, changing existing machinery
or equipment, or when acquiring new machinery or equipment in plants, workrooms and buildings.
From the outset, all parties involved (see ISO 11690-1:—, Clause 6) and, in particular, the noise experts,
should take part in the process. Noise control measures are most effective if they are integrated at the
design stage of machines, production processes, workrooms and tasks (see ISO 11690-1:—, Clause 7).
Machine operation, material transport, safety technology, ergonomics and environmental protection
should also be considered at that stage.
2 © ISO 2020 – All rights reserved

---------------------- Page: 7 ----------------------
ISO/FDIS 11690-2:2020(E)

5 Noise control at source
5.1 General
The measures described in this clause deal with the reduction of noise generated by working processes
and machines. They should be implemented at the design stage because retrospective measures can
affect operational requirements and are generally more expensive. However, they are also recommended
for existing noise sources, when practicable.
Control of noise at its source in workplaces deals in particular with the noise reduction of existing
machines, the development and selection of low noise working processes and production technologies,
the replacement of machine parts and the assessment of the results obtained.
The effectiveness of noise control at its source is based on measurements and is assessed by comparison
with the noise emission data, for example, provided by the supplier/manufacturer (see ISO 11690-1:—,
Clause 8).
5.2 Noise control at source by design
When machine noise (or noise from technical production equipment) is considered, two types of noise
generation should be distinguished: fluid dynamic noise generation (gas and/or liquid) and mechanical
generation.
Fluid dynamic noise arises from temporary fluctuations in pressure and velocity of fluids. Examples
are cornbustion processes, fans, blow-out openings and hydraulic systems.
Mechanically generated noise is caused by vibrations of machine components that are excited by
dynamic forces which are generated, for example, by impacts or out-of-balance masses. The vibrations
are transmitted to noise-radiating surfaces, such as machine casing, workpieces, etc. Examples are
tooth-wheel gears, electric motors, hammers, shakers and mechanical presses (see Figure 3).
Key
1 excitation
2 machine
3 transmission
4 radiation
Figure 3 — Generation process of mechanical noise
In order to control noise at its source, the noise-generation mechanism should be taken into account.
© ISO 2020 – All rights reserved 3

---------------------- Page: 8 ----------------------
ISO/FDIS 11690-2:2020(E)

Examples of reduction of fluid dynamic noise are the following:
a) reduction of periodical pressure fluctuations at the excitation source (e.g. in-line hydraulic
dampers);
b) reduction of flow velocities (e.g. speed-controlled fans);
c) avoidance of sudden changes in pressure (e.g. graduated vs abrupt transitions in HVAC ducting);
d) effective design of through-flow components (e.g. design layouts that do not put obstacles
immediately in front of air movers).
Examples of reduction of mechanically generated noise are the following:
e) reduction of exciting dynamic forces (e.g. by means of elastic layers to extend the impulse duration
of impacts);
f) reduction of the vibrational velocity of the machine structure at the excitation point for a given
dynamic force [e.g. by means of stiffeners or additional masses (inertia blocks)];
g) reduction of the vibration (structure-borne sound) transmission from the excitation point to the
sound-radiating surfaces [e.g. by using elastic elements and materials with high internal damping
(cast iron)];
h) reduction of the sound radiated by a vibrating structure, for example by use of
— thin walls with ribs instead of thick stiff walls,
— damping layers on thin metal sheets,
— perforated metal sheets (provided noise insulation is not required);
i) sound-insulating wrappings or thick-walled structures (thin damped metal sheets near the
radiating surface).
Further information on reducing noise at its source can be found in ISO/TR 11688-1 and ISO/TR 11688-2.
5.3 Information on noise emission
In addition to the information on noise emission given by suppliers/manufacturers in technical
documentation (see ISO 11690-1:—, Clause 8), there may be measures specific to industrial sectors.
Information on such measures can be found in databases, professional magazines, trade association
journals, etc.
For some machine families, there are lists of noise emission data obtained under specified operating
conditions. These lists can help purchasers select low-noise machines/equipment (see ISO 11690-1:—,
Annex A).
5.4 Use of low-noise machines
In some circumstances, rather than implementing costly retrospective noise control measures, it is
feasible to replace a noisy unit in a plant with a low-noise one (see Table 1).
4 © ISO 2020 – All rights reserved

---------------------- Page: 9 ----------------------
ISO/FDIS 11690-2:2020(E)

Table 1 — Examples of alternative processes with lower noise
High-noise processes Low-noise processes
Percussion riveting Compression and roll riveting
Drive by compressed air or internal combustion engine Electrical drive
Cutting or making holes in, for example, stone or con- Use of machines that can be fitted with drills or circular
crete by the use of pneumatic or internal combustion saw blades equipped with diamond teeth
percussive machines
Heading in the die Tapering/full-forward extrusion
Push cutting Pull cutting
Flow drying Radiation drying
Plasma oxygen cutting Plasma cutting under water
Cutting shock, punching Laser-beam cutting
Conventional TIG/TAG welding TIG/TAG shielded arc welding
Flame-hardening Laser-beam hardening
Fastening with rivets Pressure fixing
Stroke forming Hydraulic pressing
Spot welding Seam welding
NOTE 1 A change of the material and/or form of the component under manufacture may allow the use of low-noise
production processes.
NOTE 2 This list is by no means exhaustive.
There are also noisy operations which are not connected with fixed machines, for example from the use
of hand-held tools. These can often be the dominating noise sources in a workroom. If care is taken in
selecting the tools or the working arrangement (e.g. sound-deadened hammers, cushioned work tables,
low-noise grinding discs, magnetic damping mats, etc.), considerable noise reductions can be achieved
as shown in Figures 4 to 7.
© ISO 2020 – All rights reserved 5

---------------------- Page: 10 ----------------------
ISO/FDIS 11690-2:2020(E)

Key
X octave-band frequency, Hz
Y A-weighted sound pressure level at the work station, dB
a
Conventional steelhammer, L = 115 dB.
pA
b
Sound-deadened hammer (with little recoil), L = 107 dB.
pA
Figure 4 — Example of sound pressure level during hammering
Key
X octave-band frequency, Hz
Y A-weighted sound pressure level at the work station, dB
a
Hard grinding wheel, L = 100 dB.
pA
b
Bonded abrasive grinding wheel, L = 89 dB.
pA
Figure 5 — Example of sound pressure level when grinding during the cleaning of a cast iron
electromotor housing
6 © ISO 2020 – All rights reserved

---------------------- Page: 11 ----------------------
ISO/FDIS 11690-2:2020(E)

Key
Y A-weighted sound pressure level, dB
a
Steel working plate, 25 mm thick.
b
Steel working plate, damped by viscous material, 40 mm thick.
c
Steel working plate, 200 mm thick.
Figure 6 — Example of sound pressure level when hammering
Key
X octave-band frequency, Hz
Y A-weighted sound pressure level at the work station, dB
a
Without magnetic mat, L = 111 dB.
pA
b
With magnetic mat, L = 102 dB.
pA
Figure 7 — Example of sound pressure level when grinding a steel plate
5.5 Modification or replacement of machine components
It is possible, by replacing or modifying machine components, to reduce noise transmission inside the
machine and noise radiation by the machine surface, without affecting performance. Annex A gives
examples of such noise reduction measures.
© ISO 2020 – All rights reserved 7

---------------------- Page: 12 ----------------------
ISO/FDIS 11690-2:2020(E)

5.6 Low noise working and production technologies
It is always beneficial, if feasible, to replace a particularly noisy machine or unit in a plant with a
quieter one, for example by using a machine that works to a different principle (e.g. replacing an impact
screwdriver by a continuous direct-driven screwdriver).
With regard to existing processes, particular attention should be paid to the possibility of substituting
the process with an equally effective but quieter method.
When substituting a production process, low-noise alternatives should be systematically searched for.
The successive replacement of machines, plant items and processes by less noisy ones will in the
longterm lead to quieter working environments even though low-noise machines have to be positioned
alongside existing noisy ones.
5.7 Maintenance of machines and noise control devices
Noise emission levels from machines or processes can be unnecessarily high due to lack of maintenance,
poor lubrication, misalignment, unbalanced and loose parts, etc. Optimum operating conditions should
be maintained at all times. Any maintenance defect normally increases the noise levels.
Maintenance of noise control devices is also of prime importance. Therefore, the integrity of enclosures,
screens and silencers should be carefully monitored.
6 Noise control on the transmission path
6.1 Noise control by means of a proper spatial arrangement of the noise sources
An optimized spatial arrangement of machines can provide a substantial noise level reduction at work
stations. This is mainly applicable when planning new plants and installations but should also be
considered for existing plants.
Noise reduction can be obtained by increasing the distance between the noise sources and the work
stations (see Annex B).
6.2 Use of noise control devices
Enclosures (see Annex C), silencers (see Annex D) and screens (see Annex E) can be effective measures
for the reduction of the noise emitted from machines, installations, piping systems and openings.
An enclosure is a structure completely surrounding the machine or installation. It consists mainly of
a sound-insulating shell (metal, wood, concrete, etc.) with and without an internal sound-absorbing
lining. The achievable noise reduction depends on the insulation of airborne sound provided by the
shell and on the degree of absorption by the internal surface of the enclosure if absorption exists. In
practice, it is limited by openings, ineffective seals and by transmission of structure-borne sound. This
limitation can be minimized by using measures such as silenced openings.
The effectiveness of noise control by using enclosures, silencers or screens can be measured and
assessed by the insertion loss, the transmission loss and the reduction of sound level (see ISO 11690-1:—
, Clause 3, for definitions).
6.3 Noise control by use of sound-absorbing materials
The relationship between noise emission and noise immission is determined by sound propa
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.