EN 61094-4:1995

Measurement microphones - Part 4: Specifications for working standard microphones

Applies to working standard microphones. Specifies mechanical dimensions and certain electroacoustical characteristics for working standard microphones used in measuring systems for the determination of sound pressure to enable these microphones to be used as transfer standards in the calibration of acoustic measurement instruments.

Meßmikrofone - Teil 4: Anforderungen an Gebrauchs-Normalmikrofone

Microphones de mesure - Partie 4: Spécifications des microphones étalons de travail

S'applique aux microphones étalons de travail. Spécifie les dimensions mécaniques et certaines caractéristiques électroacoustiques des microphones étalons de travail utilisés dans les systèmes de mesure pour la détermination de la pression acoustique afin de rendre possible leur utilisation comme étalons de transfert dans l'étalonnage des appareils de mesures acoustiques.

Measurement microphones - Part 4: Specifications for working standard microphones (IEC 61094-4:1995)

General Information

• Status: Published
• Publication Date: 11-Dec-1995
• Withdrawal Date: 31-Aug-1996
• ICS: 17.140.50 - Electroacoustics
• ICS: 33.160.50 - Accessories
• Technical Committee: CLC/SR 29 - Electroacoustics
• Drafting Committee: IEC/TC 29 - IEC_TC_29
• Parallel Committee: IEC/TC 29 - IEC_TC_29
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 12-Dec-1995
• Completion Date: 12-Dec-1995
• Ref Project: SIST EN 61094-4:2002 - Measurement microphones -- Part 4: Specifications for working standard microphones

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 61094-4:2002
01-september-2002
Measurement microphones - Part 4: Specifications for working standard
microphones (IEC 61094-4:1995)

Measurement microphones -- Part 4: Specifications for working standard microphones

Meßmikrofone -- Teil 4: Anforderungen an Gebrauchs-Normalmikrofone

Microphones de mesure -- Partie 4: Spécifications des microphones étalons de travail

Ta slovenski standard je istoveten z: EN 61094-4:1995
ICS:
17.140.50 Elektroakustika Electroacoustics
33.160.50 Pribor Accessories
SIST EN 61094-4:2002 en

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

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SIST EN 61094-4:2002
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SIST EN 61094-4:2002
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SIST EN 61094-4:2002
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SIST EN 61094-4:2002
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SIST EN 61094-4:2002
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SIST EN 61094-4:2002
NORME C E I
INTERNATIONALE IEC
1094-4
INTERNATIONAL
Première édition
STANDARD
First edition
1995-11
Microphones de mesure
Partie 4:
Spécifications des microphones étalons de travail
Measurement microphones
Part 4:
Specifications for working standard microphones
de reproduction réservés — Copyright — all rights reserved
© CEI 1995 Droits
No part of this publication may be reproduced or utilized in
Aucune partie de cette publication ne peut âtre reproduite ni

utilisée sous quelque forme que ce soit et par aucun pro- any form or by any means, electronic or mechanical,

film, without permission

cédé, électronique ou mécanique, y compris la photocopie et including photocopying and micro

les microfilms. sans l'accord écrit de l'éditeur. in writing from the publisher.

Bureau Central de la Commission Electrotechnique Internationale 3, rue de Varembé Genève, Suisse

Commission Electrotechnique Internationale
CODE PRIX
International Electrotechnical Commission PRICE
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Pour prix, voir catalogue en vigueur
• •
For price, see current catalogue
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SIST EN 61094-4:2002
1094-4 ©IEC:1995 - 3 -
CONTENTS
Page
FOREWORD 5
Clause
1 Scope and object 7
2 Normative references 7
3 Definitions 9
9
3.1 Working standard microphone
3.2 Principal axis of a microphone 9
3.3 Reference plane of a microphone 9
3.4 Effective front volume of a microphone 9
3.5 Correction grid 9
4 Reference environmental conditions 9
5 Classification of working standard microphones 9
5.1 General 9
5.2 Type designation 11
11
6 Characteristics of working standard microphones
6.1 Sensitivity 11
6.2 Effective front volume 11
11
6.3 Upper limit of the dynamic range of a microphone
11
6.4 Linearity range of the microphone sensitivity level
13
6.5 Static pressure dependence of microphone sensitivity
6.6 Temperature dependence of microphone sensitivity 13
6.7 Humidity dependence of microphone sensitivity 13
6.8 Stability of microphone sensitivity 13
13
6.9 Pressure equalizing leakage
7 Specifications 15
7.1 Mechanical dimensions 15
17
7.2 Electroacoustical specifications
19
7.3 Identification markings

Annex A – Provisional ground-shield reference configuration for type WS3 microphones 23

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SIST EN 61094-4:2002
1094-4 ©IEC:1995 - 5 -
INTERNATIONAL ELECTROTECHNICAL COMMISSION
MEASUREMENT MICROPHONES
Part 4: Specifications for working standard microphones
FOREWORD

The IEC (International Electrotechnical Commision) is a worldwide organization for standardization comprising all na tional

onal Committees). The object of the IEC is to promote inte rnational cooperation on all

electrotechnical committees (IEC Na ti

ons concerning standardization in the electrical and electronic fields. To this end and in addition to other activities, the IEC

questi

publishes International Standards. Their preparation is entrusted to technical committees; any IEC National Committee interested

rnational, governmental and non-governmental organizations
in the subject dealt with may participate in this preparatory work. Inte
ational Organization for

liaising with the IEC also participate in this preparation. The IEC collaborates closely with the Inte rn

Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.

The formal decisions or agreements of the IEC on technical matters, prepared by technical committees on which all the National

rnational consensus of opinion

Committees having a special interest therein are represented, express, as nearly as possible, an inte

on the subjects dealt with.

rnational use published in the form of standards, technical reports or guides and

3) They have the form of recommendations for inte
they are accepted by the National Committees in that sense.

In order to promote internati fication, IEC National Committees undertake to apply IEC Intemation Standards transparently

4) onal uni
tional or regional standards. Any divergence between the IEC Standard and the
to the maximum extent possible in their na
er.

corresponding national or regional standard shall be clearly indicated in the latt

International Standard IEC 1094-4 has been prepared by IEC technical committee 29: Electroacoustics.

The text of this standard is based on the following documents:
DIS Report on voting
29/312/RVD
29/295/DIS

Full information on the voting for the approval of this standard can be found in the repo rt on voting indicated

in the above table.
rts, under the general title Measurement microphones:
IEC 1094 consists of the following pa
– Pa 1: 1992, Specifications for laboratory standard microphones

Part 2: 1992, Primary method for pressure calibration of laboratory standard microphones by the

reciprocity technique

3: 1995, Primary method for free-field calibration of laboratory standard microphones by the

– Part
reciprocity technique
4: 1995, Specifications for working standard microphones
– Part
Annex A is for information only.
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SIST EN 61094-4:2002
1094-4 ©IEC:1995 - 7 -
MEASUREMENT MICROPHONES
Part 4: Specifications for working standard microphones
1 Scope and object
of IEC 1094 is applicable to working standard microphones.
This part
ain electroacoustical characteristics for working standard
It specifies mechanical dimensions and ce

microphones used in measuring systems for the determination of sound pressure to enable these

microphones to be used as transfer standards in the calibration of acoustic measurement instruments.

It establishes a system for classifying working standard microphones into a number of types according to

their dimensions and properties in order to facilitate the specification of measurement systems, the

calibration of measuring systems and microphones by sound calibrators, and the interchangeability of

microphones in given measuring and calibration systems.
principle by which working standard microphones operate.
It does not specify the transduction
2 Normative references

The following normative documents contain provisions which, through reference in this text, constitute

of IEC 1094. At the time of publication, the editions indicated were valid. All normative

provisions of this pa rt
ies to agreements based on this part of IEC 1094 are
documents are subject to revision, and pa rt

encouraged to investigate the possibility of applying the most recent editions of the normative documents

listed below. Members of IEC and ISO maintain registers of currently valid International Standards.

IEC 942: 1988, Sound calibrators
1: Specifications for laboratory standard microphones
Measurement microphones - Part
IEC 1094-1: 1992,
rt 2: Primary method for pressure calibration of
IEC 1094-2: 1992, Measurement microphones - Pa
laboratory standard microphones by the reciprocity technique
3: Primary method for free-field calibration of
IEC/DIS 1094-3: 199x, Measurement microphones - Pa rt
revision of IEC 486)*
laboratory standard microphones by the reciprocity technique (
ANSI B1.1: 1982, Unified inch screw threads**
Guide to the expression of uncertainty in measurement
ISO: 1993,
* At present at the stage of draft international standard (29/294/DIS).

** Reference is given to ANSI B1.1 in the absence of an equivalent International Standard.

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SIST EN 61094-4:2002
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3 Definitions

of IEC 1094, the following definitions apply in addition to the definitions given

For the purpose of this part
in IEC 1094-1.

working standard microphone: Microphone capable of being calibrated by at least one of the

3.1
following:
a) a method specified in IEC 1094-2 or IEC 1094-3;
b) by comparison with a calibrated laboratory standard microphone;
c) by a sound calibrator as specified in IEC 942.

A working standard microphone meets ce rtain requirements on mechanical dimensions and electro-

acoustical characteristics, especially with respect to stability in time and dependence on environmental

conditions.
Line through the centre of and perpendicular to the diaphragm of
3.2 principal axis of a microphone:
the microphone.
Plane perpendicular to the principal axis immediately in front of
3.3 reference plane of a microphone:
the protection grid of the microphone.

effective front volume of a microphone: At reference conditions, the volume of air that has the

3.4

same acoustic compliance as the cavity bounded by the reference plane, the diaphragm and the outer

ace of the microphone at the reference plane, including the equivalent volume of the

cylindrical su rf

microphone configuration. The effective front volume is generally a function of frequency.

Specially shaped grid, substituted for the normal protection grid of a microphone,

3.5 correction grid:

for the purpose of changing the directivity response of the microphone, thereby changing the acoustical

classification of the microphone.
4 Reference environmental conditions
The reference environmental conditions are:
– temperature 23,0 °C
101,325 kPa
– static pressure
– relative humidity 50 %

NOTE - The reference temperature is chosen to be 23,0 °C because practical considerations require that most calibrations be

carried out at, or near, this temperature.
5 Classification of working standard microphones
5.1 General

The sound pressure in a given sound field will generally depend on position and should ideally be measured

at a point with a transducer of infinitesimally small dimensions and infinitely high acoustic impedance.

However, the finite dimensions and acoustic impedance of a real microphone, and the mounting of this

microphone cause practical measurements of sound pressure to depart from this ideal.

The effect of diffraction is accounted for by defining different sensitivities of a microphone each referring

to idealized sound fields, for example pressure, free-field, and diffuse-field sensitivities. A microphone is

usually so constructed that one of the above sensitivities is essentially independent of frequency in the

widest possible frequency range.
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SIST EN 61094-4:2002
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5.2 Type designation

Working standard microphones are described by a mnemonic system consisting of the letters WS (for

Working Standard) followed by a number representing the mechanical configuration and a third letter

representing the electroacoustical characteristic. The third letter may be P, F or D representing,

respectively, microphones having a pressure, free-field or diffuse field sensitivity, which is approximately

independent of frequency in the widest possible frequency range. The designation WS2P thus refers to a

working standard microphone of mechanical configuration 2 having a nearly constant pressure sensitivity

as a function of frequency.

The type designation does not always prevent the use of these microphones under other conditions, such

as pressure, free-field or diffuse field conditions after proper calibration.
6 Characteristics of working standard microphones
6.1 Sensitivity

The sensitivity of the microphone is the open-circuit sensitivity as defined in IEC 1094-1. If the i

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