1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA
2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any
3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. ISBN 978-0-626-22880-4 SANS 61094-5:2009Edition 1IEC 61094-5:2001Edition 1SOUTH AFRICAN NATIONAL STANDARD Measurement microphones Part 5: Methods for pre
4、ssure calibration of working standard microphones by comparison This national standard is the identical implementation of IEC 61094-5:2001 and is adopted with the permission of the International Electrotechnical Commission. Published by SABS Standards Division 1 Dr Lategan Road Groenkloof Private Ba
5、g X191 Pretoria 0001Tel: +27 12 428 7911 Fax: +27 12 344 1568 www.sabs.co.za SABS SANS 61094-5:2009 Edition 1 IEC 61094-5:2001 Edition 1 Table of changes Change No. Date Scope National foreword This South African standard was approved by National Committee SABS TC 76, Acoustics, electro-acoustics an
6、d vibration, in accordance with procedures of the SABS Standards Division, in compliance with annex 3 of the WTO/TBT agreement. This SANS document was published in July 2009. NORMEINTERNATIONALECEIIECINTERNATIONALSTANDARD61094-5Premire ditionFirst edition2001-10Microphones de mesure Partie 5:Mthodes
7、 pour ltalonnage en pressionpar comparaison des microphones talonsde travailMeasurement microphones Part 5:Methods for pressure calibration of workingstandard microphones by comparisonCommission Electrotechnique InternationaleInternational Electrotechnical CommissionPour prix, voir catalogue en vigu
8、eurFor price, see current catalogue IEC 2001 Droits de reproduction rservs Copyright - all rights reservedAucune partie de cette publication ne peut tre reproduite niutilise sous quelque forme que ce soit et par aucun procd,lectronique ou mcanique, y compris la photocopie et lesmicrofilms, sans lacc
9、ord crit de lditeur.No part of this publication may be reproduced or utilized inany form or by any means, electronic or mechanical,including photocopying and microfilm, without permission inwriting from the publisher.International Electrotechnical Commission 3, rue de Varemb Geneva, SwitzerlandTelef
10、ax: +41 22 919 0300 e-mail: inmailiec.ch IEC web site http:/www.iec.chCODE PRIXPRICE CODE QSANS 61094-5:2009This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .61094-5 IEC:2001 3 CONTENTSFOREWORD.51 Scope.72 Normative references73 Terms and defin
11、itions .74 Reference environmental conditions95 Principles of pressure calibration by comparison .95.1 Principles 95.2 Measuring the output voltages of the microphones .116 Factors influencing the pressure sensitivity .116.1 General .116.2 Microphone pressure equalizing leakage116.3 Polarising volta
12、ge 136.4 Ground shield reference configuration136.5 Pressure distribution over the diaphragms136.6 Dependence on environmental conditions 156.7 Validation 157 Calibration uncertainty components.157.1 General .157.2 Sensitivity of the reference microphone157.3 Measurements of microphone output .157.4
13、 Differences between the sound pressure at the test microphone and that atthe reference microphone 177.5 Uncertainty on pressure sensitivity level.17Annex A (informative) Examples of couplers and jigs for simultaneous excitation19Annex B (informative) Examples of couplers for sequential excitation .
14、25Annex C (informative) Determining the open-circuit sensitivity of a measurementmicrophone without using the insert-voltage method 29Annex D (informative) Typical uncertainty analysis .31Bibliography35Figure A.1 A coupler for use with WS2 microphones.19Figure A.2 A jig fitted with an LS2 and WS2 mi
15、crophone.21Figure A.3 Example arrangement of LS2 and WS2 microphones in a jig21Figure A.4 Example arrangement of LS2 and WS3 microphones in a jig21Figure B.1 A coupler for use with LS1 microphones 25Figure B.2 A coupler for use with WS2 microphones.27Table A.1 Calculated corrections to be added to t
16、he sensitivity level of the WS3microphone when using the arrangement in figure A.4 .23Table D.1 Uncertainties33SANS 61094-5:2009This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .61094-5 IEC:2001 5 INTERNATIONAL ELECTROTECHNICAL COMMISSION_MEASU
17、REMENT MICROPHONES Part 5: Methods for pressure calibration of working standardmicrophones by comparisonFOREWORD1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprisingall national electrotechnical committees (IEC National Committees). The obj
18、ect of the IEC is to promoteinternational co-operation on all questions concerning standardization in the electrical and electronic fields. Tothis end and in addition to other activities, the IEC publishes International Standards. Their preparation isentrusted to technical committees; any IEC Nation
19、al Committee interested in the subject dealt with mayparticipate in this preparatory work. International, governmental and non-governmental organizations liaisingwith the IEC also participate in this preparation. The IEC collaborates closely with the International Organizationfor Standardization (IS
20、O) in accordance with conditions determined by agreement between the twoorganizations.2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, aninternational consensus of opinion on the relevant subjects since each technical committee has representationf
21、rom all interested National Committees.3) The documents produced have the form of recommendations for international use and are published in the formof standards, technical specifications, technical reports or guides and they are accepted by the NationalCommittees in that sense.4) In order to promot
22、e international unification, IEC National Committees undertake to apply IEC InternationalStandards transparently to the maximum extent possible in their national and regional standards. Anydivergence between the IEC Standard and the corresponding national or regional standard shall be clearlyindicat
23、ed in the latter.5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for anyequipment declared to be in conformity with one of its standards.6) Attention is drawn to the possibility that some of the elements of this International Standard may be the s
24、ubjectof patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.International Standard IEC 61094-5 has been prepared by IEC technical committee 29:Electroacoustics.The text of this standard is based on the following documents:FDIS Report on voting29/495/FD
25、IS 29/497/RVDFull information on the voting for the approval of this standard can be found in the report onvoting indicated in the above table.This publication has been drafted in accordance with the ISO/IEC Directives, Part 3.Annexes A, B, C and D are for information only.The committee has decided
26、that the contents of this publication will remain unchanged until2006. At this date, the publication will be reconfirmed; withdrawn; replaced by a revised edition, or amended.SANS 61094-5:2009This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .61
27、094-5 IEC:2001 7 MEASUREMENT MICROPHONES Part 5: Methods for pressure calibration of working standardmicrophones by comparison1 ScopeThis part of IEC 61094 is applicable to working standard microphones with removableprotection grids meeting the requirements of IEC 61094-4 and to laboratory standard
28、micro-phones meeting the requirements of IEC 61094-1.This part of IEC 61094 also describes methods of determining the pressure sensitivity bycomparison with either a laboratory standard microphone that has been calibrated according toIEC 61094-2, or another working standard microphone that has been
29、calibrated accordingto this part of IEC 61094.Alternative comparison methods based on the principles described in IEC 61094-2 are possiblebut beyond the scope of this part of IEC 61094.2 Normative referencesThe following normative documents contain provisions which, through reference in this text,co
30、nstitute provisions of this part of IEC 61094. For dated references, subsequent amendmentsto, or revisions of, any of these publications do not apply. However, parties to agreementsbased on this part of IEC 61094 are encouraged to investigate the possibility of applying themost recent editions of th
31、e normative documents indicated below. For undated references, thelatest edition of the normative document referred to applies. Members of IEC and ISO maintainregisters of currently valid International Standards.IEC 61094-1, Measurement microphones Part 1: Specifications for laboratory standardmicro
32、phonesIEC 61094-2:1992, Measurement microphones Part 2: Primary method for pressurecalibration of laboratory standard microphones by the reciprocity techniqueIEC 61094-4, Measurement microphones Part 4: Specifications for working standardmicrophonesISO/IEC GUIDE EXPRES:1995, Guide to the expression
33、of uncertainty in measurement (GUM)3 Terms and definitionsFor the purpose of this part of IEC 61094, the following definitions apply in addition to thedefinitions given in IEC 61094-1.3.1reference microphonelaboratory standard microphone or working standard microphone of previously determinedpressur
34、e sensitivitySANS 61094-5:2009This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .61094-5 IEC:2001 9 3.2test microphonelaboratory standard microphone or working standard microphone to be calibrated bycomparison with a reference microphone3.3monit
35、or microphonemicrophone used to measure changes in sound pressure in a coupler3.4couplerdevice which, when fitted with microphones, forms a gas-filled cavity of predetermined shapeand dimensions and provides an acoustic coupling element between the microphones andbetween the microphones and the soun
36、d source3.5jiga device which, when fitted with microphones, holds them with their diaphragms face to faceseparated by a small distance but does not enclose the space between them4 Reference environmental conditionsThe reference environmental conditions are: temperature 23,0 C static pressure 101,325
37、 kPa relative humidity 50 %5 Principles of pressure calibration by comparison5.1 Principles5.1.1 General principleThe pressure sensitivity of a measurement microphone is defined in terms of a sound pressureapplied uniformly over the diaphragm. Consequently, the pressure sensitivity can only berealis
38、ed in principle for microphones from which the protection grid can be removed and thediaphragm be exposed to the sound waves.The principle of these comparison methods is that when the reference microphone and the testmicrophone are exposed to the same sound pressure either simultaneously or sequenti
39、ally,the ratio of their pressure sensitivities is given by the ratio of their open-circuit output voltages.The sensitivity (both modulus and phase) of the test microphone can then be calculated fromthe sensitivity of the reference microphone.The principle of the method allows the test microphone to
40、be attached to a particularpreamplifier and the sensitivity may be referred to the output of that preamplifier.Multi-frequency measurements can be performed particularly rapidly if a wideband soundsource is used and the output voltages of the microphones are analysed in narrow bands.SANS 61094-5:200
41、9This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .61094-5 IEC:2001 11 5.1.2 General principles using simultaneous excitationIn order for the two microphones to be simultaneously exposed to essentially the same soundpressure it is usually neces
42、sary for the two diaphragms to be separated by less than a tenth ofthe wavelength at the highest frequency of interest. For frequencies up to 20 kHz, this can beachieved by mounting the two microphones face to face separated by less than 1 mm in eithera coupler or a jig. Couplers usually contain an
43、integral sound source; jig mounted microphonesare usually exposed to an externally produced sound field. In order to reduce the effect ofsystematic differences in sound pressure between the two microphone positions, for examplecaused by some asymmetries, the following procedure shall be used: after
44、the ratio of themicrophone pressure sensitivities is first determined, the microphones shall be interchanged,and the measurement repeated. The sensitivity is then calculated from the mean of the tworatios. Examples of practical arrangements and precautions to be taken are given in annex A.5.1.3 Gene
45、ral principles using sequential excitationIn order for the two microphones to be sequentially exposed to essentially the same soundpressure, either the exchange of microphones shall not change the sound pressuresignificantly or any significant change shall be detected and corrected. This can be achi
46、eved byincorporating a sound source, a monitor microphone, and the test/reference microphone in acoupler. In any design of coupler, the monitor microphone shall accurately sense changes inthe sound pressure at the test/reference microphone position. Examples of practicalarrangements are given in ann
47、ex B.5.2 Measuring the output voltages of the microphonesThe output of a test or reference microphone may be determined as the open-circuit voltage byuse of the insert voltage technique (see 5.3 of IEC 61094-2) or by using a measuring systemconsisting of a high impedance microphone preamplifier and
48、a voltmeter (see annex C).The method used to measure the output of the test microphone shall be stated on anycalibration certificate.6 Factors influencing the pressure sensitivity6.1 GeneralThe pressure sensitivity of a measurement microphone may depend on environmentalconditions. Further, the defin
49、ition of the pressure sensitivity implies that certain requirementsbe fulfilled by the measurements. It is essential during a calibration that these conditions arecontrolled sufficiently well so that the resulting uncertainty components are small.6.2 Microphone pressure equalizing leakageThe cavity behind the diaphragm is normally fitted with a narrow pressure-equalizing tube topermit the static pressure to be the same on both sides of the diaphragm. Consequently, atvery low frequencies, this tube
