1、 IEC 61094-8 Edition 1.0 2012-09 INTERNATIONAL STANDARD NORME INTERNATIONALE Measurement microphones Part 8: Methods for determining the free-field sensitivity of working standard microphones by comparison Microphones de mesure Partie 8: Mthodes pour la dtermination de lefficacit en champ libre par
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16、-nous: csciec.ch. IEC 61094-8 Edition 1.0 2012-09 INTERNATIONAL STANDARD NORME INTERNATIONALE Measurement microphones Part 8: Methods for determining the free-field sensitivity of working standard microphones by comparison Microphones de mesure Partie 8: Mthodes pour la dtermination de lefficacit en
17、 champ libre par comparaison des microphones talons de travail INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE V ICS 17.140.50 PRICE CODE CODE PRIX ISBN 978-2-83220-380-4 Registered trademark of the International Electrotechnical Commission Marque dpose de la Com
18、mission Electrotechnique Internationale 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 agr. colourinside 2 61094-8 IEC:2012 CONTENTS FOREWORD . 4 1 Scope . 6 2 Normative
19、 references . 6 3 Terms and definitions . 7 4 Reference environmental conditions . 8 5 Principles of free-field calibration by comparison 8 5.1 General principle . 8 5.2 General principles using sequential excitation . 8 5.3 General principles using simultaneous excitation . 8 6 General requirements
20、 . 9 6.1 The test space . 9 6.2 Methods of establishing the free-field 9 6.2.1 General . 9 6.2.2 Using a test space with sound absorbing surfaces . 9 6.2.3 Time selective methods for obtaining the free-field sensitivity 10 6.3 The sound source 10 6.4 Reference microphone 11 6.5 Monitor microphone .
21、12 6.6 Test signals . 12 6.7 Configuration for the reference microphone and microphone under test 13 7 Factors influencing the free-field sensitivity 13 7.1 General . 13 7.2 Polarizing voltage 13 7.3 Acoustic centre of the microphone . 13 7.4 Angle of incidence and alignment with the sound source .
22、14 7.5 Mounting configuration 14 7.6 Dependence on environmental conditions 14 8 Calibration uncertainty components 14 8.1 General . 14 8.2 Sensitivity of the reference microphone . 15 8.3 Measurement of the microphone output . 15 8.4 Differences between the sound pressure applied to the reference m
23、icrophone and to the microphone under test . 15 8.5 Influence of indirect sound 15 8.6 Influence of signal processing . 16 8.7 Influence of microphone characteristics and measurement system performance 16 8.7.1 Microphone capacitance 16 8.7.2 Measurement system non-linearity 16 8.7.3 Validation of c
24、alibration system . 16 8.8 Uncertainty on free-field sensitivity level 16 Annex A (informative) Basic substitution calibration in a free-field chamber . 18 Annex B (informative) Time selective techniques . 22 Bibliography 30 61094-8 IEC:2012 3 Figure A.1 Illustration of source and receiver setup in
25、a free-field room, where the monitor microphone has been integrated into the loudspeaker 18 Figure A.2 Practical implementation in a hemi-anechoic room with a source flush-mounted in the floor 19 Figure A.3 Examples of loudspeaker sources . 21 Figure B.1 Illustration of set-up for measurement with t
26、ime selective techniques 23 Table 1 Calibration options for the reference microphone and associated typical measurement uncertainty 12 Table 2 Typical uncertainty components 17 4 61094-8 IEC:2012 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ MEASUREMENT MICROPHONES Part 8: Methods for determining the
27、free-field sensitivity of working standard microphones by comparison 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 internat
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36、r 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 a
37、pplication 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 61094-8 has been prepared by IEC
38、 technical committee 29: Electroacoustics. The text of this standard is based on the following documents: CDV Report on voting 29/752/CDV 29/759/RVC Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table. This publication ha
39、s been drafted in accordance with the ISO/IEC Directives, Part 2. 61094-8 IEC:2012 5 A list of all the parts in the IEC 61094 series, published under the general title Measurement microphones can be found on the IEC website. The committee has decided that the contents of this publication will remain
40、 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. IMPORTANT The colour inside logo on the cover page
41、 of this publication indicates that it contains colours which are considered to be useful for the correct understanding of its contents. Users should therefore print this document using a colour printer. 6 61094-8 IEC:2012 MEASUREMENT MICROPHONES Part 8: Methods for determining the free-field sensit
42、ivity of working standard microphones by comparison 1 Scope This part of the IEC 61094 series is applicable to working standard microphones meeting the requirements of IEC 61094-4. It describes methods of determining the free-field sensitivity by comparison with a laboratory standard microphone or w
43、orking standard microphone (where applicable) that has been calibrated according to either: IEC 61094-3, IEC 61094-2 or IEC 61094-5, and where factors given in IEC/TS 61094-7 have been applied, IEC 61094-6, this part of IEC 61094. Methods performed in an acoustical environment that is a good approxi
44、mation to an ideal free-field (e.g. a high quality free-field chamber), and methods that use post processing of results to minimise the effect of imperfections in the acoustical environment, to simulate free-field conditions, are both covered by this part of IEC 61094. Comparison methods based on th
45、e principles described in IEC 61094-3 are also possible but beyond the scope of this part of IEC 61094. NOTE 1 This part of IEC 61094 is also applicable to laboratory standard microphones meeting the requirements of IEC 61094-1, noting that these microphones also meet the electroacoustic specificati
46、ons for working standard microphones. NOTE 2 This part of IEC 61094 is also applicable to combinations of microphone and preamplifier where the determined sensitivity is referred to the unloaded output voltage of the preamplifier. NOTE 3 Other devices, for example, sound level meters can be calibrat
47、ed using the principles of this part of IEC 61094, but are not within the scope of this standard. 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 a
48、pplies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 61094-1, Measurement microphones Part 1: Specifications for laboratory standard microphones IEC 61094-2, Electroacoustics Measurement microphones Part 2: Primary method for pressure
49、calibration of laboratory standard microphones by the reciprocity technique IEC 61094-3, Measurement microphones Part 3: Primary method for free-field calibration of laboratory standard microphones by the reciprocity technique IEC 61094-4, Measurement microphones Part 4: Specifications for working standard microphones 61094-8 IEC:2012 7 IEC 61094-5, Measurement microphones Part 5: Methods for pressure calibra
