IEC 62585:2012

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.

Électroacoustique - Méthodes 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.

General Information

• Status: Published
• Publication Date: 24-Jul-2012
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 17.140.50 - Electroacoustics
• Technical Committee: TC 29 - Electroacoustics
• Drafting Committee: WG 17 - TC 29/WG 17
• Current Stage: PPUB - Publication issued
• Start Date: 31-Aug-2012
• Completion Date: 25-Jul-2012

Standards Content (Sample)

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

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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

– 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

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

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

FOREWORD
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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.

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