Electroacoustics - Methods to determine corrections to obtain the free-field response of a sound level meter

IEC 62585:2012 provides information on the corrections required over a range of frequencies in order for a periodic test of a sound level meter to be performed according to IEC 61672-3. These corrections include; corrections for the typical effects of reflections from the case of the sound level meter and diffraction of sound around the microphone; corrections for the deviation of the typical microphone frequency response from a uniform frequency response, where the actual microphone response cannot be measured; and corrections for the influence on the frequency response of a typical microphone of a specified windscreen and any other accessory that is part of the configuration for normal use of the particular sound level meter submitted for testing. This International Standard includes discussion about uncertainties of measurement of the required corrections. In some instances a maximum permitted expanded uncertainty for the manufacturer or testing laboratory is given. The aim of this International Standard is to ensure that the adjustment value at the calibration check frequency and all corrections are determined using consistent and appropriate methods. It is intended that this International Standard will be used by manufacturers to determine adjustment values and corrections, by laboratories performing pattern evaluation tests according to IEC 61672-2, and by laboratories performing periodic tests according to IEC 61672-3. Laboratories performing periodic tests according to IEC 61672-3 will also need to consult this International Standard to ensure that the expanded uncertainties of measurement for the corrections quoted by the manufacturer do not exceed the maximum permitted values.

Elektroakustik - Verfahren zur Ermittlung von Korrekturwerten für die Bestimmung des Freifeld-Frequenzgangs eines Schallpegelmessers

Électroacoustique - Méthode de détermination de corrections pour obtenir la réponse en champ libre d'un sonomètre

La CEI 62585:2012 donne des informations relatives aux corrections exigées sur une plage de fréquences pour effectuer un essai périodique d'un sonomètre conformément à la CEI 61672-3. Ces corrections comportent; des corrections pour les effets typiques des réflexions par le boîtier du sonomètre et la diffraction du son autour du microphone; des corrections pour l'écart de la réponse en fréquence type du microphone par rapport à une réponse en fréquence uniforme, lorsque la réponse du microphone réel ne peut pas être mesurée; et des corrections pour l'influence sur la réponse en fréquence d'un microphone type d'un écran anti-vent spécifié ou de tout autre accessoire intégré dans la configuration pour usage normal du sonomètre spécifique soumis aux essais. La présente Norme internationale comporte une discussion relative aux incertitudes de mesure des corrections exigées. Dans certains cas, une incertitude élargie maximale admissible pour le fabricant ou le laboratoire d'essais est fournie. L'objectif de la présente Norme internationale est de garantir que la valeur de réglage à la fréquence de vérification d'étalonnage ainsi que toutes les corrections, sont déterminées en utilisant des méthodes cohérentes et appropriées. La présente Norme internationale est destinée à être utilisée par les fabricants pour déterminer les valeurs de réglage et les corrections, par les laboratoires effectuant des essais d'évaluation de modèle selon la CEI 61672-2 et par les laboratoires effectuant des essais périodiques conformément à la CEI 61672-3. Les laboratoires effectuant des essais périodiques selon la CEI 61672-3 auront également besoin de consulter la présente Norme internationale pour garantir que les incertitudes de mesure élargies pour les corrections indiquées par le fabricant ne dépassent pas les valeurs maximales admises.

Elektroakustika - Metode za določanje popravkov zaradi zagotovitve odzivanja merilnika zvočne ravni v odprtem prostoru

Ta mednarodni standard podaja informacije o popravkih, ki so potrebni za obseg frekvenc, da se lahko opravi redni preskus merilnika ravni glasnosti v skladu s standardom IEC 61672-3. Ti popravki vsebujejo: - popravke za značilne učinke odbojev iz ohišja merilnika ravni glasnosti in loma zvoka okoli mikrofona; - popravke za odstope značilnega frekvenčnega odziva mikrofona od enotnega frekvenčnega odziva, kjer dejanskega frekvenčnega odziva mikrofona ni mogoče izmeriti; - popravke za vpliv značilnega mikrofona na frekvenčni razpon pri uporabi določenega filtra za mikrofon ali drugih dodatkov, ki so del konfiguracije pri normalni uporabi določenega merilnika ravni glasnosti, ki je bil določen za testiranje. Ta mednarodni standard vsebuje razpravo o nezanesljivostih pri meritvah z zahtevanimi popravki. V nekaterih primerih je podana največja dovoljena razširjena nezanesljivost za proizvajalca ali testni laboratorij. Ta največja dovoljena razširjena nezanesljivost izključuje vse komponente zaradi spremenljivosti različnih vzorcev artefaktov (na primer mikrofona ali filtra za mikrofon). Treba je opozoriti, da če so navedene velike nezanesljivosti meritev za vsakega od posameznih popravkov in če združene odgovarjajo za konfiguracijo testiranega merilnika ravni glasnosti, potem te velike nezanesljivosti morda ne bodo v skladu z največjimi dovoljenimi razširjenimi nezanesljivostmi pri merjenju, ki so podane v tabeli A.1 v standardu IEC 61672-1:-1, in povzročijo neujemanje merilnika ravni glasnosti s standardom IEC 61672-1. Ta mednarodni standard tudi opisuje metode za določanje teh popravkov na želenem frekvenčnem območju in razloži nastavljivo vrednost na frekvenci za preverjanje kalibracije, ki jo bo navedel proizvajalec merilnika ravni glasnosti (zahteva ga tudi standard IEC 61672-3). Ko proizvajalec merilnika ravni glasnosti priporoča uporabo kalibratorja zvoka, primerjalne sponke ali elektrostatičnega sprožila za periodično testiranje akustičnega odziva merilnika ravni glasnosti pri različnih frekvencah, ta mednarodni standard opisuje metode merjenja popravkov, ki so potrebni, da se označba na merilniku ravni glasnosti prilagodi ustrezni ravni v odprtem prostoru pri izbranemu frekvenčnemu obsegu. Ti popravki veljajo za določen model kalibratorja zvoka, primerjalne sponke ali elektrostatičnega sprožila, mikrofona in merilnika ravni glasnosti (zahteva ga tudi standard IEC 61672-3). Cilj tega mednarodnega standarda je, da zagotovi konsistentne in primerne metode določanja nastavljive vrednosti na frekvenci za preverjanje kalibracije in vseh popravkov. Ta mednarodni standard je namenjen proizvajalcem, da ugotovijo nastavljive vrednosti in popravke s pomočjo laboratorijev, ki izvajajo teste ocene vzorcev v skladu s standardom IEC 61672-2 in periodične teste v skladu s standardom IEC 61672-3. Laboratoriji, ki izvajajo periodične teste v skladu s standardom IEC 61672-3, bodo morali tudi upoštevati ta mednarodni standard, da lahko zagotovijo, da razširjene nezanesljivosti merjenja za popravke, ki jih navaja proizvajalec, ne presežejo največjih dovoljenih vrednosti. Popravki, pridobljeni z uporabo metod iz tega mednarodnega standarda, so rezultat merjenja z uporabo vzorcev naprav. Mogoče je, da ti popravki niso popolnoma reprezentativni bodisi za vse proizvedene serije bodisi v daljšem časovnem obdobju. Priporočeno je, da meritve ponavljate v rednih presledkih, da ni potrebno spreminjati popravkov, ki so navedeni v priročniku z navodili. Ta mednarodni standard ne pokriva določenih ohišij, ki imajo na merilniku ravni glasnosti pritrjen mikrofon, ki se uporablja za zvočna polja naključne pojavnosti. Te informacije so podane v standardu IEC 61183.

General Information

Status
Published
Publication Date
04-Oct-2012
Technical Committee
Drafting Committee
Current Stage
6060 - Document made available
Due Date
05-Oct-2012
Completion Date
05-Oct-2012

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SLOVENSKI STANDARD
SIST EN 62585:2012
01-december-2012
(OHNWURDNXVWLND0HWRGH]DGRORþDQMHSRSUDYNRY]DUDGL]DJRWRYLWYHRG]LYDQMD
PHULOQLND]YRþQHUDYQLYRGSUWHPSURVWRUX

Electroacoustics - methods to determine corrections to obtain the free-field response of a

sound level meter

Elektroakustik - Verfahren zur Ermittlung von Korrekturwerten für die Bestimmung des

Freifeld-Frequenzgangs eines Schallpegelmessers

Electroacoustique - méthode de détermination de corrections pour obtenir la réponse en

champ libre d'un sonomètre
Ta slovenski standard je istoveten z: EN 62585:2012
ICS:
17.140.50 Elektroakustika Electroacoustics
SIST EN 62585:2012 en

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

---------------------- Page: 1 ----------------------
SIST EN 62585:2012
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SIST EN 62585:2012
EUROPEAN STANDARD
EN 62585
NORME EUROPÉENNE
October 2012
EUROPÄISCHE NORM
ICS 17.140.50
English version
Electroacoustics -
Methods to determine corrections to obtain the free-field response
of a sound level meter
(IEC 62585:2012)
Électroacoustique - Elektroakustik -
Méthode de détermination de corrections Verfahren zur Ermittlung
pour obtenir la réponse en champ libre von Korrekturwerten für die Bestimmung
d'un sonomètre des Freifeld-Frequenzgangs eines
(CEI 62585:2012) Schallpegelmessers
(IEC 62585:2012)

This European Standard was approved by CENELEC on 2012-08-29. 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.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Management Centre: Avenue Marnix 17, B - 1000 Brussels

© 2012 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 62585:2012 E
---------------------- Page: 3 ----------------------
SIST EN 62585:2012
EN 62585:2012 - 2 -
Foreword

The text of document 29/770/FDIS, future edition 1 of IEC 62585, prepared by IEC/TC 29

"Electroacoustics" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as

EN 62585:2012.
The following dates are fixed:
(dop) 2013-05-29
• latest date by which the document has
to be implemented at national level by
publication of an identical national
standard or by endorsement
(dow) 2015-08-29
• latest date by which the national
standards conflicting with the
document have to be withdrawn

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 62585:2012 was approved by CENELEC as a European

Standard without any modification.

In the official version, for Bibliography, the following notes have to be added for the standards indicated:

IEC 61094-8 NOTE Harmonised as EN 61094-8.
IEC 61260 NOTE Harmonised as EN 61260.
IEC 61094-2 NOTE Harmonised as EN 61094-2.
IEC 61094-3 NOTE Harmonised as EN 61094-3.
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SIST EN 62585:2012
- 3 - EN 62585:2012
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 When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD

applies.
Publication Year Title EN/HD Year
IEC 60942 - Electroacoustics - Sound calibrators EN 60942 -
IEC 61094-1 - Measurement microphones - EN 61094-1 -
Part 1: Specifications for laboratory
standard microphones
IEC 61094-5 - Measurement microphones - EN 61094-5 -
Part 5: Methods for pressure calibration
of working standard microphones by
comparison
IEC 61094-6 - Measurement microphones - EN 61094-6 -
Part 6: Electrostatic actuators for
determination of frequency response
IEC/TS 61094-7 - Measurement microphones - - -
Part 7: Values for the difference between
free-field and pressure sensitivity levels
of laboratory standard microphones
IEC 61183 - Electroacoustics - Random-incidence EN 61183 -
and diffuse-field calibration of sound
level meters
IEC 61672-1 - Electroacoustics - Sound level meters - EN 61672-1 -
Part 1: Specifications
IEC 61672-2 - Electroacoustics - Sound level meters - EN 61672-2 -
Part 2: Pattern evaluation tests
IEC 61672-3 - Electroacoustics - Sound level meters - EN 61672-3 -
Part 3: Periodic tests
ISO/IEC Guide 98-3 - Uncertainty of measurement - - -
Part 3: Guide to the expression of
uncertainty in measurement (GUM)
ISO/IEC Guide 99 - International vocabulary of metrology - Basic - -
and general concepts and associated terms
(VIM)
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SIST EN 62585:2012
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SIST EN 62585:2012
IEC 62585
Edition 1.0 2012-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electroacoustics – Methods to determine corrections to obtain the free-field
response of a sound level meter
Électroacoustique – Méthodes de détermination de corrections pour obtenir la
réponse en champ libre d'un sonomètre
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX X
ICS 17.140.50 ISBN 978-2-83220-290-6

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
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SIST EN 62585:2012
– 2 – 62585 © IEC:2012
CONTENTS

FOREWORD ........................................................................................................................... 4

INTRODUCTION ..................................................................................................................... 6

1 Scope ............................................................................................................................... 7

2 Normative references ....................................................................................................... 8

3 Terms and definitions ....................................................................................................... 8

4 Reference environmental conditions ................................................................................. 9

5 Uncertainties of measurement .......................................................................................... 9

6 General requirements for measurement of adjustment value and corrections .................. 10

7 Submission and inspection ............................................................................................. 12

8 Determination of the adjustment value at the calibration check frequency ....................... 12

9 Determination of corrections for the typical effects of reflections from the case of

the sound level meter and diffraction of sound around the microphone ........................... 13

10 Determination of corrections for the deviation of the microphone free-field

frequency response from a uniform frequency response ................................................. 13

11 Determination of corrections for the use of windscreens and similar accessories ............ 14

12 Determination of corrections over a range of frequencies when a sound calibrator

is recommended for use by the sound level meter manufacturer ..................................... 14

13 Determination of corrections over a range of frequencies when a comparison

coupler is recommended for use by the sound level meter manufacturer ........................ 15

14 Determination of corrections over a range of frequencies when an electrostatic

actuator is recommended for use by the sound level meter manufacturer ....................... 16

15 Documentation ............................................................................................................... 16

Annex A (normative) Calibration check frequency – Determination of the adjustment

value .................................................................................................................................... 18

Annex B (normative) Determination of the effects of reflections from the case of the

sound level meter and diffraction of sound around the microphone ....................................... 20

Annex C (normative) Determination of the effects of the use of windscreens and

similar accessories ............................................................................................................... 21

Annex D (informative) Determination of corrections for use with sound calibrators to

determine equivalent free-field response at all frequencies of interest .................................. 22

Annex E (informative) Determination of corrections for use with comparison couplers

to determine equivalent free-field frequency response at all frequencies of interest .............. 25

Annex F (informative) Determination of corrections for use with electrostatic actuators

to determine equivalent free-field frequency response at all frequencies of interest .............. 28

Annex G (informative) Comparison techniques..................................................................... 31

Annex H (informative) Exact one-twelfth-octave frequencies ................................................ 34

Annex I (informative) Example calculations of expanded uncertainty of measurement .......... 36

Bibliography .......................................................................................................................... 40

Figure 1 – Mounting methods for the sound level meter ........................................................ 11

Figure A.1 – Diagrammatic representation of factors for consideration in optimising

adjustment value at the calibration check frequency ............................................................. 19

Figure D.1 – Measurement steps using a sound calibrator .................................................... 22

Figure E.1 – Measurement steps using a comparison coupler ............................................... 25

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SIST EN 62585:2012
62585 © IEC:2012 – 3 –

Figure F.1 – Measurement steps using an electrostatic actuator ........................................... 28

Table H.1 – Exact frequencies for one-twelfth-octave steps over one decade ....................... 35

Table I.1 – Description of likely uncertainty components ....................................................... 37

Table I.2 – Uncertainty example for a frequency of 1 kHz ..................................................... 38

Table I.3 – Uncertainty example for a frequency of 8 kHz ..................................................... 39

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SIST EN 62585:2012
– 4 – 62585 © IEC:2012
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROACOUSTICS –
METHODS TO DETERMINE CORRECTIONS TO OBTAIN
THE FREE-FIELD RESPONSE OF A SOUND LEVEL METER
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote

international co-operation on all questions concerning standardization in the electrical and electronic fields. To

this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,

Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC

Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested

in the subject dealt with may participate in this preparatory work. International, governmental and non-

governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely

with the International Organization for Standardization (ISO) in accordance with conditions determined by

agreement between the two organizations.

2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

consensus of opinion on the relevant subjects since each technical committee has representation from all

interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

transparently to the maximum extent possible in their national and regional publications. Any divergence

between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

the latter.

5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity

assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any

services carried out by independent certification bodies.

6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

members of its technical committees and IEC National Committees for any personal injury, property damage or

other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

Publications.

8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 62585 has been prepared by IEC technical committee 29:

Electroacoustics.
The text of this International Standard is based on the following documents:
FDIS Report on voting
29/770/FDIS 29/782/RVD

Full information on the voting for the approval of this International Standard can be found in

the report on voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

---------------------- Page: 10 ----------------------
SIST EN 62585:2012
62585 © IEC:2012 – 5 –

The committee has decided that the contents of this publication will remain unchanged until

the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data

related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
---------------------- Page: 11 ----------------------
SIST EN 62585:2012
– 6 – 62585 © IEC:2012
INTRODUCTION

The performance specification International Standard for sound level meters, IEC 61672-1,

requires that at least one model of sound calibrator, conforming to the requirements of

IEC 60942 be specified in the instruction manual for checking and maintaining the correct

indication on the display of the sound level meter at the calibration check frequency. The

sound level meter manufacturer specifies the adjustment value to be applied to obtain the

required indication on the display in response to the sound pressure level generated by the

sound calibrator, in order to optimize performance over the complete frequency range.

In addition, various corrections need to be available over a range of frequencies in order for a

periodic test of a sound level meter to be performed according to IEC 61672-3. For example,

corrections are needed for any effects of the sound level meter case or of accessories such

as windscreens on the equivalent free-field sound level. Information on these corrections is

also required by users of sound level meters and sound calibrators on a regular basis.

Also, a manufacturer producing a sound level meter to the specifications of IEC 61672-1, may

recommend, in the instruction manual, the use of a sound calibrator, comparison coupler or

electrostatic actuator to determine the acoustical response of a sound level meter at various

frequencies. In this case the manufacturer is required to provide corrections to obtain

equivalent sound levels that would be displayed under reference environmental conditions in

response to plane progressive sinusoidal waves that are incident from the reference direction

at each frequency used for periodic testing. These corrections will either be given in the

instruction manual, or the instruction manual will state where they can be found.

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SIST EN 62585:2012
62585 © IEC:2012 – 7 –
ELECTROACOUSTICS –
METHODS TO DETERMINE CORRECTIONS TO OBTAIN
THE FREE-FIELD RESPONSE OF A SOUND LEVEL METER
1 Scope

This International Standard provides information on the corrections required over a range of

frequencies in order for a periodic test of a sound level meter to be performed according to

IEC 61672-3. These corrections include:

• corrections for the typical effects of reflections from the case of the sound level meter and

diffraction of sound around the microphone;

• corrections for the deviation of the typical microphone frequency response from a uniform

frequency response, where the actual microphone response cannot be measured;

• corrections for the influence on the frequency response of a typical microphone of a

specified windscreen and any other accessory that is part of the configuration for normal

use of the particular sound level meter submitted for testing.

This International Standard includes discussion about uncertainties of measurement of the

required corrections. In some instances a maximum permitted expanded uncertainty for the

manufacturer or testing laboratory is given. This maximum permitted expanded uncertainty

excludes any component due to the variability of different samples of artefact (for example,

microphone or windscreen). It should be noted that if large uncertainties of measurement are

quoted for each of the individual corrections, when they are combined to account for the

configuration of sound level meter under test, the large individual uncertainties may result in a

failure to conform to the maximum permitted expanded uncertainties of measurement given in

Table A.1 of IEC 61672-1:— and hence a failure of the sound level meter to conform to

IEC 61672-1

In addition, this International Standard describes methods for determining these corrections,

over the frequency range of interest, and explains the adjustment value at the calibration

check frequency to be quoted by the manufacturer of the sound level meter (also required by

IEC 61672-3).

When the sound level meter manufacturer recommends the use of a sound calibrator,

comparison coupler, or an electrostatic actuator for periodic testing of the acoustical response

of a sound level meter at various frequencies, this International Standard describes methods

of measurement of the corrections required to adjust the indication on the sound level meter

to an equivalent free-field level, over the frequency range of interest. These corrections relate

to a specific model of sound calibrator, comparison coupler or electrostatic actuator,

microphone and sound level meter (also required by IEC 61672-3).

The aim of this International Standard is to ensure that the adjustment value at the calibration

check frequency and all corrections are determined using consistent and appropriate

methods.

It is intended that this International Standard will be used by manufacturers to determine

adjustment values and corrections, by laboratories performing pattern evaluation tests

according to IEC 61672-2, and by laboratories performing periodic tests according to

IEC 61672-3. Laboratories performing periodic tests according to IEC 61672-3 will also need

to consult this International Standard to ensure that the expanded uncertainties of

___________
Second edition to be published. (A revision of 61672-1:2002.)
---------------------- Page: 13 ----------------------
SIST EN 62585:2012
– 8 – 62585 © IEC:2012

measurement for the corrections quoted by the manufacturer do not exceed the maximum

permitted values.

The corrections obtained by use of the methods given in this International Standard are the

result of measurements made using samples of the devices. It is possible that these

corrections may not be totally representative either for all batches produced or over time.

Repeating the measurements at regular intervals is recommended to ensure that no changes

are required to the corrections stated in the instruction manual.

This International Standard does not specifically cover the case where the sound level meter

is fitted with a microphone intended for use in random-incidence sound fields, as information

is given in IEC 61183.
2 Normative references

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.
IEC 60942, Electroacoustics – Sound calibrators

IEC 61094-1, Measurement microphones – Part 1: Specifications for laboratory standard

microphones

IEC 61094-5, Measurement microphones – Part 5: Methods for pressure calibration of working

standard microphones by comparison

IEC 61094-6, Measurement microphones – Part 6: Electrostatic actuators for determination of

frequency response

IEC/TS 61094-7, Measurement microphones – Part 7: Values for the difference between free-

field and pressure sensitivity levels of laboratory standard microphones

IEC 61183, Electroacoustics-Random-incidence and diffuse-field calibration of sound level

meters
IEC 61672-1: — , Electroacoustics – Sound level meters – Part 1: Specifications

IEC 61672-2, Electroacoustics – Sound level meters – Part 2: Pattern evaluation tests

IEC 61672-3, Electroacoustics – Sound level meters – Part 3: Periodic tests

ISO/IEC Guide 98-3, Uncertainty of measurement – Part 3: Guide to the expression of

uncertainty in measurement (GUM:1995)

ISO/IEC Guide 99, International vocabulary of metrology – Basic and general concepts and

associated terms (VIM)
3 Terms and definitions

For the purposes of this document, the terms and definitions given in the ISO/IEC Guide 99,

as well as the following apply.
___________
Second edition to be published. (A revision of 61672-1:2002.)
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SIST EN 62585:2012
62585 © IEC:2012 – 9 –
3.1
adjustment value at the calibration check frequency

value, at the calibration check frequency, for adjusting the sensitivity of the sound level meter,

as specified by the manufacturer to be added to the displayed value of the sound level meter

to obtain the stated sound pressure level from the calibrator while the sound level meter is

exposed to the sound pressure in the calibrator, in order to optimise performance of the sound

level meter over the complete frequency range
Note 1 to entry: The adjustment value is expressed in decibels (dB).
3.2
microphone
microphone cartridge

electroacoustic transducer by which electrical signals are obtained from acoustic oscillations

3.3
microphone reference point

point specified on, or close to, the microphone to describe the position of the microphone

Note 1 to entry: The microphone reference point will usually be at the centre of the diaphragm of the microphone.

3.4
free-field correction for sound level meter

value, at a particular frequency, that, during calibration or verification, is added to the level

displayed by the sound level meter to obtain its response to a progressive sound wave in the

free field of sound pressure level equal to that produced or simulated by the sound source,

dependent on the specific models and configurations of sound level meter and sound source

Note 1 to entry: The IEC 61672 series permits the use of a sound calibrator, a comparison coupler or an

electrostatic actuator as the sound source. The values of the corrections for these sound sources are not

necessarily equal.

Note 2 to entry: The value of this correction depends on the direction of incidence of the progressive sound wave.

Note 3 to entry: When the free-field correction is stated, the reference direction is assumed unless an alternative

direction is given.

Note 4 to entry: A measurement with an electrostatic actuator is not an absolute measurement, but is referenced

to a sensitivity at a particular frequency, for example the calibration check frequency.

Note 5 to entry: Corrections are expressed in decibels (dB).
4 Reference environmental conditions

Reference environmental conditions for specifying the adjustment value and corrections are:

– temperature: 23 °C
– static air pressure: 101,325 kPa
– relative humidity: 50 %
5 Uncertainties of measurement

Laboratories performing measurements of the corrections shall calculate the uncertainties

associated with all measurements in accordance with the guidelines given in ISO/IEC Guide

98-3. Actual expanded uncertainties shall be calculated for a level of confidence of 95 %,

using the necessary coverage factor, which shall be stated.

NOTE 1 Generally a coverage factor of 2 approximates to a level of confidence of 95 %, unless the contributions

are such that it is necessary to use a different coverage factor to maintain the 95 % level of confidence.

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SIST EN 62585:2012
– 10 – 62585 © IEC:2012

The maximum permitted expanded uncertainties of measurement are given separately in the

following clauses for the appropriate corrections. If the actual expanded uncertainty of

measurement exceeds any of the maximum permitted values, the measurement shall not be

used to evaluate the corrections provided in the instruction manual for the sound level meter.

NOTE 2 It is not possible to derive corrections for use in demonstrating conformance of the sound level meter to

the requirements of IEC 61672-1 if the actual expanded uncertainty of measurement exceeds any of the maximum

permitted values.

Calculation of the expanded uncertainty of measurement for a particular measurement should

consider all relevant components. An example calculation is given in Annex I.
6 General requirements for measurement of adjustment value and corrections

For all measurements the laboratory shall use instruments that have been calibrated for the

appropriate quantities at appropriate intervals. As required, the calibrations shall be traceable

to national standards.

Measurements shall be performed within the following ranges of environmental conditions:

80 kPa to 105 kPa for static air pressure, 20 °C to 26 °C for air temperature and 25 % to 70 %

for relative humidity. If the measurements are performed at a static pressure below 97 kPa an

additional uncertainty component shall be included in the calculation of the uncertainty of the

measured corrections to account for the deviations from the values at reference conditions. If

specific data are not available this additional uncertainty component shall be a
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