IEC_TR_61094-10-2022.pdf

IEC TR 61094-10 Edition 1.0 2022-08 TECHNICAL REPORT Electroacoustics Measurement microphones Part 10:Absolute pressure calibration of microphones at low frequencies using calculable pistonphones IEC TR 61094-10:2022-08(en)colourinside THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2022 IEC,Geneva,Switzerland All rights reserved.Unless otherwise specified,no part of this publication may be reproduced or utilized in any form or by any means,electronic or mechanical,including photocopying and microfilm,without permission in writing from either IEC or IECs member National Committee in the country of the requester.If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,please contact the address below or your local IEC member National Committee for further information.IEC Secretariat Tel.:+41 22 919 02 11 3,rue de Varemb infoiec.ch CH-1211 Geneva 20 www.iec.ch Switzerland About the IEC The International Electrotechnical Commission(IEC)is the leading global organization that prepares and publishes International Standards for all electrical,electronic and related technologies.About IEC publications The technical content of IEC publications is kept under constant review by the IEC.Please make sure that you have the latest edition,a corrigendum or an amendment might have been published.IEC publications search-webstore.iec.ch/advsearchform The advanced search enables to find IEC publications by a variety of criteria(reference number,text,technical committee,).It also gives information on projects,replaced and withdrawn publications.IEC Just Published-webstore.iec.ch/justpublished Stay up to date on all new IEC publications.Just Published details all new publications released.Available online and once a month by email.IEC Customer Service Centre-webstore.iec.ch/csc If you wish to give us your feedback on this publication or need further assistance,please contact the Customer Service Centre:salesiec.ch.IEC Products&Services Portal-products.iec.ch Discover our powerful search engine and read freely all the publications previews.With a subscription you will always have access to up to date content tailored to your needs.Electropedia-www.electropedia.org The worlds leading online dictionary on electrotechnology,containing more than 22 300 terminological entries in English and French,with equivalent terms in 19 additional languages.Also known as the International Electrotechnical Vocabulary(IEV)online.IEC TR 61094-10 Edition 1.0 2022-08 TECHNICAL REPORT Electroacoustics Measurement microphones Part 10:Absolute pressure calibration of microphones at low frequencies using calculable pistonphones INTERNATIONAL ELECTROTECHNICAL COMMISSION ICS 17.140.50 ISBN 978-2-8322-4374-9 Registered trademark of the International Electrotechnical Commission Warning!Make sure that you obtained this publication from an authorized distributor.colourinside 2 IEC TR 61904-10:2022 IEC 2022 CONTENTS FOREWORD.4 1 Scope.6 2 Normative references.6 3 Terms and definitions.6 4 Reference environmental conditions.7 5 Principles of absolute pressure calibration of microphones using a calculable pistonphone.7 5.1 General principle.7 5.2 Basic expressions.7 5.3 Heat conduction correction.9 5.4 Operating frequency range.9 6 General characteristics.9 6.1 The pistonphone.9 6.2 Measuring the piston volume velocity.10 6.3 Test signals.10 6.4 Mounting the microphone and pressure-equalizing tube.10 6.5 Measuring the output voltages of the microphones.10 7 Factors influencing the pressure sensitivity.10 7.1 General.10 7.2 Polarizing voltage.11 7.3 Shield configuration.11 7.4 Dependence on environmental conditions.11 7.4.1 General.11 7.4.2 Static pressure.11 7.4.3 Temperature.11 7.4.4 Humidity.12 7.5 Vibration.12 7.6 Distortion.12 8 Calibration uncertainty components.12 8.1 General.12 8.2 Measurements of microphone output voltage.12 8.3 Piston.12 8.3.1 Frequency.12 8.3.2 Measurement of the volume velocity.12 8.4 Acoustic transfer impedance.13 8.4.1 Cavity properties.13 8.4.2 Physical quantities.13 8.5 Microphone parameters.13 8.5.1 Front cavity.13 8.5.2 Acoustic impedance.13 8.5.3 Polarizing voltage.14 8.6 Uncertainty on pressure sensitivity level.14 Annex A(informative)Example designs of pistonphones using laser interferometry.16 IEC TR 61904-10:2022 IEC 2022 3 Annex B(informative)Measurement uncertainties.18 B.1 General.18 B.2 Example of a typical uncertainty analysis.18 B.2.1 General.18 B.2.2 Uncertainty budget.18 B.2.3 Combined and expanded uncertainties.19 Bibliography.20 Figure 1 Equivalent circuit for evaluating the sound pressure over the exposed surface of the diaphragm of the microphone.8 Figure A.1 Schematic cross-section of a laser pistonphone.16 Figure A.2 Example of laser pistonphone.17 Figure A.3 Example of laser pistonphone.17 Table 1 Uncertainty components.14 Table B.1 Example of uncertainty budget at 1 Hz.19 4 IEC TR 61904-10:2022 IEC 2022 INTERNATIONAL ELECTROTECHNICAL COMMISSION