IEC 61400-11:2012
(Main)Wind turbines - Part 11: Acoustic noise measurement techniques
Wind turbines - Part 11: Acoustic noise measurement techniques
IEC 61400-11:2012 presents measurement procedures that enable noise emissions of a wind turbine to be characterised. This involves using measurement methods appropriate to noise emission assessment at locations close to the machine, in order to avoid errors due to sound propagation, but far away enough to allow for the finite source size. The procedures described are different in some respects from those that would be adopted for noise assessment in community noise studies. They are intended to facilitate characterisation of wind turbine noise with respect to a range of wind speeds and directions. Standardisation of measurement procedures will also facilitate comparisons between different wind turbines. This new edition constitutes a technical revision, introducing new principles for data reduction procedures.
Éoliennes - Partie 11: Techniques de mesure du bruit acoustique
l’IEC 61400-11:2012 spécifie les procédures de mesure qui permettent de caractériser les émissions sonores d’une éolienne. Cette démarche implique l’utilisation de méthodes de mesure appropriées à l’évaluation des émissions sonores à des emplacements proches de la machine, afin d’éviter les erreurs dues à la propagation du son, mais toutefois suffisamment éloignés pour permettre de déterminer la dimension des sources finies. Les procédures décrites sont différentes à certains égards de celles qui seraient adoptées pour l’évaluation du bruit dans le cadre des études portant sur le bruit ambiant. Ces procédures sont destinées à faciliter la caractérisation du bruit émis par une éolienne par rapport à une plage donnée de vitesses et de directions du vent. La normalisation des procédures de mesure facilite également les comparaisons entre différentes éoliennes. Cette nouvelle édition constitue une révision technique, introduisant de nouveaux principes concernant les procédures de traitement des données.
General Information
Relations
Buy Standard
Standards Content (Sample)
IEC 61400-11 ®
Edition 3.0 2012-11
INTERNATIONAL
STANDARD
colour
inside
Wind turbines –
Part 11: Acoustic noise measurement techniques
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
either IEC or IEC's member National Committee in the country of the requester.
If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,
please contact the address below or your local IEC member National Committee for further information.
IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé Fax: +41 22 919 03 00
CH-1211 Geneva 20 info@iec.ch
Switzerland www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.
About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.
Useful links:
IEC publications search - www.iec.ch/searchpub Electropedia - www.electropedia.org
The advanced search enables you to find IEC publications The world's leading online dictionary of electronic and
by a variety of criteria (reference number, text, technical electrical terms containing more than 30 000 terms and
committee,…). definitions in English and French, with equivalent terms in
It also gives information on projects, replaced and additional languages. Also known as the International
withdrawn publications. Electrotechnical Vocabulary (IEV) on-line.
IEC Just Published - webstore.iec.ch/justpublished Customer Service Centre - webstore.iec.ch/csc
Stay up to date on all new IEC publications. Just Published If you wish to give us your feedback on this publication
details all new publications released. Available on-line and or need further assistance, please contact the
also once a month by email. Customer Service Centre: csc@iec.ch.
IEC 61400-11 ®
Edition 3.0 2012-11
INTERNATIONAL
STANDARD
colour
inside
Wind turbines –
Part 11: Acoustic noise measurement techniques
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XA
ICS 27.180 ISBN 978-2-83220-463-4
– 2 – 61400-11 © IEC:2012(E)
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 Symbols and units . 12
5 Outline of method . 13
6 Instrumentation . 14
6.1 Acoustic instruments . 14
6.1.1 General . 14
6.1.2 Equipment for the determination of the equivalent continuous A-
weighted sound pressure level. 14
6.1.3 Equipment for the determination of A-weighted 1/3-octave band
spectra . 14
6.1.4 Equipment for the determination of narrow band spectra . 14
6.1.5 Microphone with measurement board and windscreen . 14
6.1.6 Acoustical calibrator . 16
6.1.7 Data recording/playback systems . 16
6.2 Non-acoustic Instruments . 16
6.2.1 General . 16
6.2.2 Anemometers . 16
6.2.3 Electric power transducer . 17
6.2.4 Other instrumentation . 17
6.3 Traceable calibration . 17
7 Acoustic measurements and measurement procedures . 17
7.1 Acoustic measurement positions . 17
7.2 Acoustic measurements . 20
7.2.1 General . 20
7.2.2 Acoustic measurement requirements . 20
7.2.3 A-weighted sound pressure level . 21
7.2.4 A-weighted 1/3-octave band measurements . 21
7.2.5 A-weighted narrow band measurements . 21
7.2.6 Optional acoustic measurements at positions 2, 3 and 4 . 21
7.2.7 Other optional measurements . 21
8 Non-acoustic measurements . 21
8.1 General . 21
8.2 Wind speed measurements . 22
8.2.1 Determination of the wind speed during wind turbine operation. 22
8.2.2 Wind speed measurements during background noise measurements . 23
8.3 Downwind direction . 24
8.4 Other atmospheric conditions . 24
8.5 Rotor speed and pitch angle measurement . 24
9 Data reduction procedures. 24
9.1 General methodology for sound power levels and 1/3-octave band levels . 24
9.2 Calculation of sound pressure levels . 27
61400-11 © IEC:2012(E) – 3 –
9.2.1 General . 27
9.2.2 Calculation of average sound spectra and uncertainty per bin . 27
9.2.3 Calculation of average wind speed and uncertainty per bin . 29
9.2.4 Calculation of noise levels at bin centres including uncertainty . 30
9.3 Apparent sound power levels . 31
9.4 Apparent sound power levels with reference to wind speed in 10 m height . 32
9.5 Tonal audibility . 33
9.5.1 General methodology for tonality . 33
9.5.2 Identifying possible tones . 34
9.5.3 Classification of spectral lines within the critical band . 34
9.5.4 Identified tone . 37
9.5.5 Determination of the tone level . 37
9.5.6 Determination of the masking noise level . 37
9.5.7 Determination of tonality . 37
9.5.8 Determination of audibility . 38
9.5.9 Background noise . 38
10 Information to be reported . 39
10.1 General . 39
10.2 Characterisation of the wind turbine . 39
10.3 Physical environment . 39
10.4 Instrumentation . 40
10.5 Acoustic data . 40
10.6 Non-acoustic data . 41
10.7 Uncertainty . 41
Annex A (informative) Other possible characteristics of wind turbine noise emission
and their quantification . 42
Annex B (informative) Assessment of turbulence intensity . 44
Annex C (informative) Assessment of measurement uncertainty . 45
Annex D (informative) Apparent roughness length . 47
Annex E (informative) Characterization of a secondary wind screen. 49
Annex F (normative) Small wind turbines . 53
Annex G (informative) Air absorption . 57
Bibliography . 58
Figure 1 – Mounting of the microphone . 15
Figure 2 – Picture of microphone and measurement board . 16
Figure 3 – Standard pattern for microphone measurement positions (plan view) . 18
Figure 4 – Illustration of the definitions of R and slant distance R . 19
0 1
Figure 5 – Acceptable meteorological mast position (hatched area) . 22
Figure 6 – Flowchart showing the data reduction procedure . 26
Figure 7 – Flowchart for determining tonal audibility for each wind speed bin . 33
Figure 8 – Illustration of L level in the critical band . 35
70 %
Figure 9 – Illustration of lines below the L + 6 dB criterion . 36
70 %
Figure 10 – Illustration of L level and lines classified as masking. 36
pn,avg
Figure 11 – Illustration of classifying all spectral lines . 37
Figure E.1 – Example 1 of a secondary wind screen . 50
– 4 – 61400-11 © IEC:2012(E)
Figure E.2 – Example 2 of secondary wind screen . 51
Figure E.3 – Example on insertion loss from Table E.1 . 52
Figure F.1 – Allowable region for meteorological mast position as a function of β –
Plan view . 54
Figure F.2 – Example immission noise map . 56
Figure G.1 – Example of 1/3-octave spectrum . 57
Table C.1 – Examples of possible values of type B uncertainty components relevant
for apparent sound power spectra . 46
Table C.2 – Examples of possible values of type B uncertainty components for wind
speed determination relevant for apparent sound power spectra . 46
Table D.1 – Roughness length . 47
Table E.1 – Example on reporting of insertion loss. 51
61400-11 © IEC:2012(E) – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___
...
IEC 61400-11 ®
Edition 3.1 2018-06
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
colour
inside
Wind turbines –
Part 11: Acoustic noise measurement techniques
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
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.
IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.
About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.
IEC Catalogue - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
The stand-alone application for consulting the entire The world's leading online dictionary of electronic and
bibliographical information on IEC International Standards, electrical terms containing 21 000 terms and definitions in
Technical Specifications, Technical Reports and other English and French, with equivalent terms in 16 additional
documents. Available for PC, Mac OS, Android Tablets and languages. Also known as the International Electrotechnical
iPad. Vocabulary (IEV) online.
IEC publications search - webstore.iec.ch/advsearchform IEC Glossary - std.iec.ch/glossary
The advanced search enables to find IEC publications by a 67 000 electrotechnical terminology entries in English and
variety of criteria (reference number, text, technical French extracted from the Terms and Definitions clause of
committee,…). It also gives information on projects, replaced IEC publications issued since 2002. Some entries have been
and withdrawn publications. collected from earlier publications of IEC TC 37, 77, 86 and
CISPR.
IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published IEC Customer Service Centre - webstore.iec.ch/csc
details all new publications released. Available online and If you wish to give us your feedback on this publication or
also once a month by email. need further assistance, please contact the Customer Service
Centre: sales@iec.ch.
IEC 61400-11 ®
Edition 3.1 2018-06
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
colour
inside
Wind turbines –
Part 11: Acoustic noise measurement techniques
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.180 ISBN 978-2-8322-5826-2
IEC 61400-11 ®
Edition 3.1 2018-06
CONSOLIDATED VERSION
REDLINE VERSION
colour
inside
Wind turbines –
Part 11: Acoustic noise measurement techniques
– 2 – IEC 61400-11:2012+AMD1:2018 CSV
© IEC 2018
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
INTRODUCTION to the Amendment . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 Symbols and units . 12
5 Outline of method . 13
6 Instrumentation . 14
6.1 Acoustic instruments . 14
6.1.1 General . 14
6.1.2 Equipment for the determination of the equivalent continuous A-
weighted sound pressure level. 14
6.1.3 Equipment for the determination of A-weighted 1/3-octave band
spectra . 14
6.1.4 Equipment for the determination of narrow band spectra . 14
6.1.5 Microphone with measurement board and windscreen . 14
6.1.6 Acoustical calibrator . 16
6.1.7 Data recording/playback systems . 16
6.2 Non-acoustic Instruments . 16
6.2.1 General . 16
6.2.2 Anemometers . 16
6.2.3 Electric power transducer . 17
6.2.4 Other instrumentation . 17
6.3 Traceable calibration . 17
7 Acoustic measurements and measurement procedures . 17
7.1 Acoustic measurement positions . 17
7.2 Acoustic measurements . 20
7.2.1 General . 20
7.2.2 Acoustic measurement requirements . 20
7.2.3 A-weighted sound pressure level . 21
7.2.4 A-weighted 1/3-octave band measurements . 21
7.2.5 A-weighted narrow band measurements . 21
7.2.6 Optional acoustic measurements at positions 2, 3 and 4 . 21
7.2.7 Other optional measurements . 22
7.2.8 Combining measurement series . 22
8 Non-acoustic measurements . 22
8.1 General . 22
8.2 Wind speed measurements . 22
8.2.1 Determination of the wind speed during wind turbine operation. 23
8.2.2 Wind speed measurements during background noise measurements . 24
8.3 Downwind direction . 24
8.4 Other atmospheric conditions . 25
8.5 Rotor speed and pitch angle measurement . 25
9 Data reduction procedures. 25
© IEC 2018
9.1 General methodology for sound power levels and 1/3-octave band levels . 25
9.2 Calculation of sound pressure levels . 28
9.2.1 General . 28
9.2.2 Calculation of average sound spectra and uncertainty per bin . 28
9.2.3 Calculation of average wind speed and uncertainty per bin . 30
9.2.4 Calculation of noise levels at bin centres including uncertainty . 31
9.3 Apparent sound power levels . 32
9.4 Apparent sound power levels with reference to wind speed in 10 m height . 33
9.5 Tonal audibility . 34
9.5.1 General methodology for tonality . 34
9.5.2 Identifying possible tones . 37
9.5.3 Classification of spectral lines within the critical band . 37
9.5.4 Identified tone . 40
9.5.5 Determination of the tone level . 40
9.5.6 Determination of the masking noise level . 40
9.5.7 Determination of tonality . 40
9.5.8 Determination of audibility . 41
9.5.9 Background noise . 41
10 Information to be reported . 42
10.1 General . 42
10.2 Characterisation of the wind turbine . 42
10.3 Physical environment . 42
10.4 Instrumentation . 43
10.5 Acoustic data . 43
10.6 Non-acoustic data . 44
10.7 Uncertainty . 44
Annex A (informative) Other possible characteristics of wind turbine noise emission
and their quantification . 45
Annex B (informative) Assessment of turbulence intensity . 47
Annex C (informative) Assessment of measurement uncertainty . 48
Annex D (informative) Apparent roughness length . 50
Annex E (informative) Characterization of a secondary wind screen. 52
Annex F (normative) Small wind turbines . 56
Annex G (informative) Air absorption . 60
Annex H (normative) Data treatment for measurement series on different days or with
substantially different conditions . 61
Bibliography . 62
Figure 1 – Mounting of the microphone . 15
Figure 2 – Picture of microphone and measurement board . 16
Figure 3 – Standard pattern for microphone measurement positions (plan view) . 18
Figure 4 – Illustration of the definitions of R and slant distance R . 20
0 1
Figure 5 – Acceptable meteorological mast position (hatched area) . 23
Figure 6 – Flowchart showing the data reduction procedure . 27
Figure 7 – Flowchart for determining tonal audibility for each wind speed bin . 36
Figure 8 – Illustration of L level in the critical band . 38
70 %
– 4 – IEC 61400-11:2012+AMD1:2018 CSV
© IEC 2018
Figure 9 – Illustration of lines below the L + 6 dB criterion . 39
70 %
Figure 10 – Illustration of L level and lines classified as masking. 39
pn,avg
Figure 11 – Illustration of classifying all spectral lines . 40
Figure E.1 – Example 1 of a secondary wind screen . 53
Figure E.2 – Example 2 of secondary wind screen . 54
...
IEC 61400-11 ®
Edition 3.0 2012-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Wind turbines –
Part 11: Acoustic noise measurement techniques
Éoliennes –
Partie 11: Techniques de mesure du bruit acoustique
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
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.
Droits de reproduction réservés. Sauf indication contraire, 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
et les microfilms, sans l'accord écrit de l'IEC ou du Comité national de l'IEC du pays du demandeur. Si vous avez des
questions sur le copyright de l'IEC ou si vous désirez obtenir des droits supplémentaires sur cette publication, utilisez
les coordonnées ci-après ou contactez le Comité national de l'IEC de votre pays de résidence.
IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.
About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.
IEC Catalogue - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
The stand-alone application for consulting the entire The world's leading online dictionary of electronic and
bibliographical information on IEC International Standards, electrical terms containing 21 000 terms and definitions in
Technical Specifications, Technical Reports and other English and French, with equivalent terms in 16 additional
documents. Available for PC, Mac OS, Android Tablets and languages. Also known as the International Electrotechnical
iPad. Vocabulary (IEV) online.
IEC publications search - webstore.iec.ch/advsearchform IEC Glossary - std.iec.ch/glossary
The advanced search enables to find IEC publications by a 67 000 electrotechnical terminology entries in English and
variety of criteria (reference number, text, technical French extracted from the Terms and Definitions clause of
committee,…). It also gives information on projects, replaced IEC publications issued since 2002. Some entries have been
and withdrawn publications. collected from earlier publications of IEC TC 37, 77, 86 and
CISPR.
IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published IEC Customer Service Centre - webstore.iec.ch/csc
details all new publications released. Available online and If you wish to give us your feedback on this publication or
also once a month by email. need further assistance, please contact the Customer Service
Centre: sales@iec.ch.
A propos de l'IEC
La Commission Electrotechnique Internationale (IEC) est la première organisation mondiale qui élabore et publie des
Normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.
A propos des publications IEC
Le contenu technique des publications IEC est constamment revu. Veuillez vous assurer que vous possédez l’édition la
plus récente, un corrigendum ou amendement peut avoir été publié.
Catalogue IEC - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
Application autonome pour consulter tous les renseignements
Le premier dictionnaire en ligne de termes électroniques et
bibliographiques sur les Normes internationales,
électriques. Il contient 21 000 termes et définitions en anglais
Spécifications techniques, Rapports techniques et autres
et en français, ainsi que les termes équivalents dans 16
documents de l'IEC. Disponible pour PC, Mac OS, tablettes
langues additionnelles. Egalement appelé Vocabulaire
Android et iPad.
Electrotechnique International (IEV) en ligne.
Recherche de publications IEC -
Glossaire IEC - std.iec.ch/glossary
webstore.iec.ch/advsearchform
67 000 entrées terminologiques électrotechniques, en anglais
La recherche avancée permet de trouver des publications IEC et en français, extraites des articles Termes et Définitions des
en utilisant différents critères (numéro de référence, texte, publications IEC parues depuis 2002. Plus certaines entrées
comité d’études,…). Elle donne aussi des informations sur les antérieures extraites des publications des CE 37, 77, 86 et
projets et les publications remplacées ou retirées. CISPR de l'IEC.
IEC Just Published - webstore.iec.ch/justpublished Service Clients - webstore.iec.ch/csc
Restez informé sur les nouvelles publications IEC. Just Si vous désirez nous donner des commentaires sur cette
Published détaille les nouvelles publications parues. publication ou si vous avez des questions contactez-nous:
Disponible en ligne et aussi une fois par mois par email. sales@iec.ch.
IEC 61400-11 ®
Edition 3.0 2012-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Wind turbines –
Part 11: Acoustic noise measurement techniques
Éoliennes –
Partie 11: Techniques de mesure du bruit acoustique
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 27.180 ISBN 978-2-8322-6321-1
– 2 – IEC 61400-11:2012 © IEC:2012
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 Symbols and units . 12
5 Outline of method . 13
6 Instrumentation . 14
6.1 Acoustic instruments . 14
6.1.1 General . 14
6.1.2 Equipment for the determination of the equivalent continuous A-
weighted sound pressure level. 14
6.1.3 Equipment for the determination of A-weighted 1/3-octave band
spectra . 14
6.1.4 Equipment for the determination of narrow band spectra . 14
6.1.5 Microphone with measurement board and windscreen . 14
6.1.6 Acoustical calibrator . 16
6.1.7 Data recording/playback systems . 16
6.2 Non-acoustic Instruments . 16
6.2.1 General . 16
6.2.2 Anemometers . 16
6.2.3 Electric power transducer . 17
6.2.4 Other instrumentation . 17
6.3 Traceable calibration . 17
7 Acoustic measurements and measurement procedures . 17
7.1 Acoustic measurement positions . 17
7.2 Acoustic measurements . 20
7.2.1 General . 20
7.2.2 Acoustic measurement requirements . 20
7.2.3 A-weighted sound pressure level . 21
7.2.4 A-weighted 1/3-octave band measurements . 21
7.2.5 A-weighted narrow band measurements . 21
7.2.6 Optional acoustic measurements at positions 2, 3 and 4 . 21
7.2.7 Other optional measurements . 21
8 Non-acoustic measurements . 21
8.1 General . 21
8.2 Wind speed measurements . 22
8.2.1 Determination of the wind speed during wind turbine operation. 22
8.2.2 Wind speed measurements during background noise measurements . 23
8.3 Downwind direction . 24
8.4 Other atmospheric conditions . 24
8.5 Rotor speed and pitch angle measurement . 24
9 Data reduction procedures. 24
9.1 General methodology for sound power levels and 1/3-octave band levels . 24
9.2 Calculation of sound pressure levels . 27
9.2.1 General . 27
9.2.2 Calculation of average sound spectra and uncertainty per bin . 27
9.2.3 Calculation of average wind speed and uncertainty per bin . 29
9.2.4 Calculation of noise levels at bin centres including uncertainty . 30
9.3 Apparent sound power levels . 31
9.4 Apparent sound power levels with reference to wind speed in 10 m height . 32
9.5 Tonal audibility . 33
9.5.1 General methodology for tonality . 33
9.5.2 Identifying possible tones . 34
9.5.3 Classification of spectral lines within the critical band . 34
9.5.4 Identified tone . 37
9.5.5 Determination of the tone level . 37
9.5.6 Determination of the masking noise level . 37
9.5.7 Determination of tonality . 37
9.5.8 Determination of audibility . 38
9.5.9 Background noise . 38
10 Information to be reported . 39
10.1 General . 39
10.2 Characterisation of the wind turbine . 39
10.3 Physical environment . 39
10.4 Instrumentation . 40
10.5 Acoustic data . 40
10.6 Non-acoustic data . 41
10.7 Uncertainty . 41
Annex A (informative) Other possible characteristics of wind turbine noise emission
and their quantification . 42
Annex B (informative) Assessment of turbulence intensity . 44
Annex C (informative) Assessment of measurement uncertainty .
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.