BS-EN-61094-1-1995 IEC-61094-1-1992.pdf

BRITISH STANDARD BS EN 61094-1:1995 IEC 1094-1: 1992 (including corrigendum 1993) Measurement microphones Part 1: Specifications for laboratory standard microphones The European Standard EN 61094-1:1994 has the status of a British Standard UDC 621.395.61:621.317.08:534.86:534.6.08 Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 11 09:20:11 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 61094-1:1995 This British Standard, having been prepared under the direction of the Electrotechnical Sector Board, was published under the authority of the Standards Board and comes into effect on 15 May 1995 © BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference EPL/29 Draft for comment 94/205711 DC ISBN 0 580 24002 9 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee EPL/29, Electroacoustics, upon which the following bodies were represented: British Association of Otolaryngologists British Hearing Aid Industry Association British Medical Association British Society of Audiology British Telecommunications plc Confederation of British Industry Department of Health Department of Trade and Industry (National Physical Laboratory) Health and Safety Executive Institute of Acoustics Institute of Sound and Vibration Research Institution of Electrical Engineers Medical Research Council Ministry of Defence Royal Aeronautical Society Royal National Institute for Deaf People Society of Environmental Engineers University of Exeter Amendments issued since publication Amd. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 11 09:20:11 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 61094-1:1995 © BSI 11-1999i Contents Page Committees responsibleInside front cover National forewordii Foreword2 Text of EN 61094-13 List of referencesInside back cover Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 11 09:20:11 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 61094-1:1995 ii © BSI 11-1999 National foreword This British Standard has been prepared by Technical Committee EPL/29 and is the English language version of EN 61094-1:1994, Measurement microphones Part 1: Specifications for laboratory standard microphones, published by the European Committee for Electrotechnical Standardization (CENELEC). It is identical with IEC 1094-1:1992, together with its corrigendum 1993 published by the International Electrotechnical Commission (IEC). A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-reference Publication referred toCorresponding British Standard IEC 50 (801):1984BS 4727 Glossary of electrotechnical, power, telecommunications, electronics, lighting and colour terms BS 4727-3 Terms particular to telecommunications and electronics BS 4727-3:Group 08:1985 Acoustics and electroacoustics terminology Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN title page, pages 2 to 10, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 11 09:20:11 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM EN 61094-1 August 1994 UDC 621.395.61:621.317.08:534.86:534.6.08 Descriptors: Electroacoustics, microphones, laboratory equipment, standard measures, specifications, definitions, classifications, characteristics, dimensions English version Measurement microphones Part 1: Specifications for laboratory standard microphones (IEC 1094-1:1992 + corrigendum 1993) Microphones de mesure Partie 1: Spécifications des microphones étalons de laboratoire (CEI 1094-1:1992 + corrigendum 1993) Meßmikrofone Teil 1: Festlegungen für Laboratoriums-Normalmikrofone (IEC 1094-1:1992 + corrigendum 1993) This European Standard was approved by CENELEC on 1994-03-08. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels © 1994 Copyright reserved to CENELEC members Ref. No. EN 61094-1:1994 E Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 11 09:20:11 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 61094-1:1994 © BSI 11-1999 2 Foreword The CENELEC questionnaire procedure, performed for finding out whether or not the International Standard IEC 1094-1:1992 and its corrigendum February 1993 could be accepted without textual changes, has shown that no common modifications were necessary for acceptance as a European Standard. The reference document was submitted to the CENELEC members for formal vote and was approved by CENELEC as EN 61094-1 on 8 March 1994. The following dates were fixed: For products which have complied with the relevant national standard before 1995-03-15, as shown by the manufacturer or by a certification body, this previous standard may continue to apply for production until 2000-03-15. Annexes designated “normative” are part of the body of the standard. In this standard, Annex ZA is normative. Contents Page Foreword2 1Scope3 2Normative references3 3Definitions3 3.1condenser microphone3 3.2laboratory standard microphone3 3.3open-circuit voltage3 3.4pressure sensitivity of a microphone3 3.4.1 pressure sensitivity level of a microphone3 3.5free-field sensitivity of a microphone4 3.5.1 free-field sensitivity level of a microphone4 3.6diffuse-field sensitivity of a microphone4 3.6.1 diffuse-field sensitivity level of a microphone4 3.7electrical impedance of a microphone4 3.8acoustic impedance of a microphone4 3.8.1 equivalent volume of a microphone4 3.9static pressure coefficient of microphone pressure sensitivity level5 Page 3.10temperature coefficient of microphone pressure sensitivity level5 3.11relative humidity coefficient of microphone pressure sensitivity level5 3.12stability coefficient of microphone pressure sensitivity level5 4Reference environmental conditions5 5Classification of laboratory standard microphones5 5.1General5 5.2Type designation5 6Characteristics of laboratory standard microphones6 6.1Sensitivity6 6.2Acoustic impedance6 6.3Upper limit of the dynamic range of a microphone6 6.4Static pressure dependence of microphone sensitivity6 6.5Temperature dependence of microphone sensitivity6 6.6Humidity dependence of microphone sensitivity6 6.7Electrical insulation resistance6 6.8Stability of microphone sensitivity6 6.9Pressure equalizing leakage6 7Specifications7 7.1Mechanical dimensions7 7.2Ground shield reference configuration8 7.3Electroacoustical specifications8 7.4Identification markings9 Annex ZA (normative) Other international publications quoted in this standard with the references of the relevant European publications10 Figure 1 Mechanical configurations of microphones7 Figure 2 Mechanical attachment to microphone, showing the ground-shield reference configuration8 Table 1 Nominal mechanical dimensions and tolerance limits for laboratory standard microphones in Figure 17 Table 2 Nominal mechanical dimensions and tolerance limits of ground-shield reference configuration in Figure 28 Table 3 Electroacoustical specifications for laboratory standard microphones9 latest date of publication of an identical national standard(dop) 1995-03-15 latest date of withdrawal of conflicting national standards(dow) 1995-03-15 Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 11 09:20:11 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 61094-1:1994 © BSI 11-19993 1 Scope This part of IEC 1094 specifies mechanical dimensions and certain electroacoustic characteristics for condenser microphones used as laboratory standards for the realization of the unit of sound pressure and for sound pressure measurements of the highest attainable accuracy. The specifications are intended to ensure that primary calibration by the reciprocity method can be readily carried out. establishes a system for classifying laboratory standard condenser microphones into a number of types according to their dimensions and properties in order to facilitate the specification of calibration methods, the conduct of interlaboratory comparisons involving the calibration of the same microphones in different laboratories, and the inter-changeability of microphones in a given calibration system. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this part of IEC 1094. At the time of publication of this standard, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of IEC 1094 are encouraged to investigate the possibility of applying the most recent editions of the standards listed below. Members of IEC and ISO maintain registers of currently valid International Standards. IEC 50(801):1984, Advance edition of the International Electrotechnical Vocabulary Chapter 801: Acoustics and electro-acoustics. ANSI B-1.1:1982, Unified inch screw threads1). 3 Definitions For the purpose of this part of IEC 1094, the following definitions apply. Remark The underlined symbols are complex quantities. 3.1 condenser microphone microphone that operates by variation of electrical capacitance IEV 801-06-13 NOTEOnly condenser microphones operating by a virtually constant charge obtained from an external polarizing voltage applied from a source of suitably high internal resistance are considered. 3.2 laboratory standard microphone condenser microphone capable of being calibrated to a very high accuracy by a primary method such as the closed coupler reciprocity method, and meeting certain severe requirements on mechanical dimensions and electroacoustical characteristics, especially with respect to stability in time and dependence on environmental conditions 3.3 open-circuit voltage alternating voltage appearing at the electrical output terminals of a microphone as measured by the insert voltage technique when the microphone is attached to the ground shield configuration specified in 7.2 but is otherwise unloaded Unit: volt, V. NOTEOwing to the capacitive nature of the microphone, the voltage at the electrical terminals depends on the electrical load presented by the mechanical and electrical attachment of the microphone to a preamplifier. For this reason, preamplifiers used for measuring the open-circuit voltage of a microphone should fulfil the requirements of 7.2. 3.4 pressure sensitivity of a microphone For a sinusoidal signal of given frequency and for given environmental conditions, the quotient of the open-circuit voltage of the microphone by the sound pressure acting over the exposed surface of the diaphragm (i.e. at the acoustical terminals of the microphone), the sound pressure being uniformly applied over the surface of the diaphragm. This quotient is a complex quantity but when phase information is of no interest the pressure sensitivity may denote its modulus only. Unit: volt per pascal, V/Pa. 3.4.1 pressure sensitivity level of a microphone logarithm of the ratio of the modulus of the pressure sensitivityto a reference sensitivity. The pressure sensitivity level in decibels is 20 lgwhere the reference sensitivity Mr is 1 V/Pa Unit: decibel, dB. 1) Reference is given to ANSI B-1.1 in the absence of an equivalent International Standard. Mp Mp Mr (), Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 11 09:20:11 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 61094-1:1994 4 © BSI 11-1999 3.5 free-field sensitivity of a microphone For a sinusoidal plane progressive wave of given frequency, for a specified direction of sound incidence, and for given environmental conditions, the quotient of the open-circuit voltage of the microphone by the sound pressure that would exist at the position of the acoustic centre of the microphone in the absence of the microphone. This quotient is a complex quantity, but when phase information is of no interest, the free-field sensitivity may denote its modulus only. Unit: volt per pascal, V/Pa. NOTE 1At frequencies sufficiently low for the disturbance of the sound field by the microphone to be negligible, the free-field sensitivity approaches the pressure sensitivity (see 6.9 for practical limitations). NOTE 2The position of the acoustic centre is a function of frequency. 3.5.1 free-field sensitivity level of a microphone logarithm of the ratio of the modulus of the free-field sensitivityto a reference sensitivity.The free-field sensitivity level in decibels is 20 lgwhere the reference sensitivity Mr is 1 V/Pa Unit: decibel, dB. 3.6 diffuse-field sensitivity of a microphone For a sinusoidal signal of given frequency in a diffuse sound field and for given environmental conditions, the quotient of the open-circuit voltage of the microphone by the sound pressure that would exist at the position of the acoustic centre of the microphone in the absence of the microphone. Unit: volt per pascal, V/Pa. NOTE 1At frequencies sufficiently low for the disturbance of the sound field by the microphone to be negligible, the diffuse-field sensitivity approaches the pressure sensitivity (see 6.9 for practical limitations). NOTE 2The position of the acoustic centre is a function of frequency. 3.6.1 diffuse-field sensitivity level of a microphone logarithm of the ratio of the modulus of the diffuse-field sensitivityto a reference sensitivity. The diffuse-field sensitivity level in decibels is 20 lgwhere the reference sensitivity Mr is 1 V/Pa Unit: decibel, dB. 3.7 electrical impedance of a microphone for a sinusoidal signal of given frequency, the complex quotient of the voltage applied across its electrical terminals by the resulting current through those term