EN 61094-3:2016

SLOVENSKI STANDARD
01-november-2016
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Measurement microphones - Part 3: Primary method for free-field calibration of
laboratory standard microphones by the reciprocity technique (IEC 61094-3:2016)
Microphones de mesure - Partie 3 : Méthode de base pour l'étalonnage en champ libre
des microphones étalons de laboratoire par la méthode de réciprocité (IEC 61094-
3:2016)
Ta slovenski standard je istoveten z: EN 61094-3:2016
ICS:
17.140.50 Elektroakustika Electroacoustics
33.160.50 Pribor Accessories
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 61094-3
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2016
ICS 17.140.50; 33.160.50 Supersedes EN 61094-3:1995
English Version
Electroacoustics - Measurement microphones - Part 3: Primary
method for free-field calibration of laboratory standard
microphones by the reciprocity technique
(IEC 61094-3:2016)
Électroacoustique - Microphones de mesure - Partie 3: Messmikrofone - Teil 3: Primärverfahren zur Freifeld-
Méthode primaire pour l'étalonnage en champ libre des Kalibrierung von Laboratoriums-Normalmikrofonen nach der
microphones étalons de laboratoire par la méthode de Reziprozitätsmethode
réciprocité (IEC 61094-3:2016)
(IEC 61094-3:2016)
This European Standard was approved by CENELEC on 2016-07-19. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2016 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 61094-3:2016 E
European foreword
The text of document 29/873/CDV, future edition 2 of IEC 61094-3, prepared by IEC TC 29,
Electroacoustics, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as
The following dates are fixed:
(dop) 2017-04-19
• latest date by which the document has
to be implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national (dow) 2019-07-19
standards conflicting with the
document have to be withdrawn
This document supersedes EN 61094-3:1995.

Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such patent
rights.
Endorsement notice
The text of the International Standard IEC 61094-3:2016 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following note has to be added for the standard indicated:
IEC 61094-8:2012 NOTE Harmonized as EN 61094-8:2012.

Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod), the relevant EN/HD

applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here:
www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 61094-1 2000 Measurement microphones -- Part 1: EN 61094-1 2000
Specifications for laboratory standard
microphones
IEC 61094-2 2009 Electroacoustics - Measurement EN 61094-2 2009
microphones -- Part 2: Primary method for
the pressure calibration of laboratory
standard microphones by the reciprocity
technique
ISO 9613-1 -  Acoustics; attenuation of sound during - -
propagation outdoors; part_1: calculation of
the absorption of sound by the atmosphere
IEC/TS 61094-7 -  Measurement microphones -- Part 7: Values - -
for the difference between free-field and
pressure sensitivity levels of laboratory
standard microphones
ISO/IEC Guide 98-3 -  Uncertainty of measurement - Part 3: Guide - -
to the expression of uncertainty in
measurement (GUM:1995)
IEC 61094-3 ®
Edition 2.0 2016-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electroacoustics – Measurement microphones –

Part 3: Primary method for free-field calibration of laboratory standard

microphones by the reciprocity technique

Électroacoustique – Microphones de mesure –

Partie 3: Méthode primaire pour l’étalonnage en champ libre des microphones

étalons de laboratoire par la méthode de réciprocité

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.140.50; 33.160.50 ISBN 978-2-8322-3478-5

– 2 – IEC 61094-3:2016 © IEC 2016
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references. 6
3 Terms and definitions . 6
4 Reference environmental conditions . 7
5 Principles of free-field calibration by reciprocity . 7
5.1 General principles . 7
5.1.1 General . 7
5.1.2 General principles using three microphones . 7
5.1.3 General principles using two microphones and an auxiliary sound
source . 8
5.2 Basic expressions . 8
5.3 Insert voltage technique . 9
5.4 Free-field receiving characteristics of a microphone . 9
5.5 Free-field transmitting characteristics of a microphone . 10
5.6 Reciprocity procedure . 11
5.7 Final expressions for the free-field sensitivity . 11
5.7.1 Method using three microphones . 11
5.7.2 Method using two microphones and an auxiliary sound source . 12
6 Factors influencing the free-field sensitivity . 12
6.1 General . 12
6.2 Polarizing voltage . 12
6.3 Shield configuration . 12
6.4 Acoustic conditions . 13
6.5 Position of the acoustic centre of a microphone . 13
6.6 Dependence on environmental conditions . 14
6.6.1 General . 14
6.6.2 Static pressure . 14
6.6.3 Temperature . 14
6.6.4 Humidity . 14
6.6.5 Transformation to reference environmental conditions. 14
6.7 Considerations concerning measurement space . 15
7 Calibration uncertainty components . 15
7.1 General . 15
7.2 Electrical transfer impedance . 15
7.3 Deviations from ideal free-field conditions . 15
7.4 Attenuation of sound in air . 16
7.5 Polarizing voltage . 16
7.6 Physical properties of air . 16
7.7 Imperfection of theory . 16
7.8 Uncertainty on free-field sensitivity level . 17
Annex A (informative) Values for the position of the acoustic centre . 19
Annex B (normative) Values of the air attenuation coefficient . 20
B.1 General . 20
B.2 Calculation procedure . 20

IEC 61094-3:2016 © IEC 2016 – 3 –
Annex C (informative) Environmental influence on the sensitivity of microphones . 23
C.1 General . 23
C.2 Dependence on static pressure . 23
C.3 Dependence on temperature . 23
Annex D (informative) Application of time selective techniques for removal of
unwanted reflections and acoustic interference between microphones . 25
D.1 General . 25
D.2 Practical considerations . 25
D.2.1 Signal-to-noise ratio . 25
D.2.2 Reflections from walls and measurement rig . 25
D.3 Frequency limitations . 26
D.3.1 General . 26
D.3.2 Measurements based on frequency sweeps . 26
D.3.3 Measurements based on pure tones . 26
D.4 Generating missing portions of the frequency response previous to
transforming to the time-domain. . 27
D.4.1 General . 27
D.4.2 Missing frequencies below the minimum measurement frequency . 27
D.4.3 Missing frequencies above the maximum measured frequency . 27
D.4.4 Filtering the extended frequency response . 28
Bibliography .
...