1、BSI BS*EN*b1094- 4 96 Lb24bb9 0544927 109 BRITISH STANDARD Specification for Measurement microphones Part 4. Specifications for working standard microphones The European Standard EN 610944 : 1995 has the status of a British Standard ICs 17.140.60 33.160.50 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS
2、 PERMITTED BY COPYRIGH“ LA. BS EN 61094-4 : 1996 IEC 1094-4 : 1995 ES1 BS*EN*bL094- 4 96 9 1624669 0544928 045 9 Amd. No. Date BS EN 61094-4 : 1996 Text affected This British Standard, having been prepared under the direction of the Eiectmtechnical Sector Board, was published under the authority of
3、the Standards Board and comes into effect on 15 July 1996 o BSI 1996 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technid Committee EPy29, Electroacoustics, upon which the following bodies were represented British Association of Otola,ryn
4、gologiStS British Hearing Aid Indm Association British Medid Association British Society of Audiology British Telecommunications pic Confederation of British Industry Department of Health Department of Trade and Industry (National Physical Laboratory) Health and Safety Executive Institute of Acousti
5、cs 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 The foiiowing BSI references relate to the work on
6、 this standard: Committee reference EPLn9 Draft for comment 94t202601 DC ISBN O 680 25909 9 BSI BS*EN*b1094- 4 9b m Lb24bb9 0544929 TBL m BS EN 61094-4 : 1996 Contents page Committees responsible Inside front cover National foreword ii Foreword 2 Text of EN 61094-4 3 O BSI 1996 i BS EN 61094-4 : 199
7、6 National foreword This British Standard has been prepared by Technicai Committee EPy29 and is the English language version of EN 61W : 1995, Measurement micrqphrmes Part 4: Specifiatbns for wwng standard micmphones, published by the European Committee for Electrotechnical Standardization (CENELEC)
8、. It is identical with IEC 1094-4, first edition 1995. Cross-references Publication referred to HD 556 S1: 1991 (IEC 942 : 1988) EN 61094-1 : 1994 EN 61094-2 : 1993 (EC 1094-2 : 1992) (IEC 1094-1 : 1992) EN 610943 : 1995 (IEC 10943 : 1995) Corresponding British Standard BS 7189 ; 1989 Speccatiun for
9、 sound caLWorS BS EN 61094 Sp 1994 Prmary method forpesuw calilwatha of labomtory standard micmphones by Uze w b) by comparison with a calibrated laboratory standard microphone; c) by a sound calibrator as specified in IEC 942. A working standard microphone meets certain requirements on mechanical d
10、imensions and electro- acoustical characteristics, especially with respect to stability in time and dependence on environmental conditions. 3.2 principal axis of a microphone: Line through the centre of and perpendicular to the diaphragm of the microphone. 3.3 reference plane of a microphone: Plane
11、perpendicular to the principal axis immediately in front of the protection grid of the microphone. 3.4 effective front volume of a microphone: At reference conditions, the volume of air that has the same acoustic compliance as the cavity bounded by the reference plane, the diaphragm and the outer cy
12、lindrical surface of the microphone at the reference plane, including the equivalent volume of the microphone configuration. The effective front volume is generally a function of frequency. 3.5 correction grid: Specially shaped grid, substituted for the normal protection grid of a microphone, for th
13、e 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 - static pressure 101,325 kPa - relative humidity 50% NOTE - 7he
14、reference tgmperature Is chosen to be 23,O C because praclicai considerations require that mt cabmtbns be carried oui at. M near, this temperaure. 5 Classification of working standard microphones The sound pressure in a gven sound field will generally depend on position and should ideally be measure
15、d 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 eff
16、ect of diffraction is accounted for by defining different sensitivities of a microphone each referring to idealized sound fields, for example pressure, free-field, and diff use-field sensitivities. A microphone is usually so constructed that one of the above sensitivities is essentially independent
17、of frequency in the widest possible frequency range. BSI BS*EN*bLO94- 4 96 H 1624669 0544935 285 Page 6 EN 61094-4: 1996 5.2 Type designation Working standard microphones are described by a mnemonic system consisting of the letters WS (for Norking Standard) followed by a number representing the mech
18、anical configuration and a third letter representing the electroacoustical characteristic. The third letter may be Pl 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 freq
19、uency 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, f
20、ree-field or diffuse field conditions after proper calibration. 6 Characteristics of working standard mlcrophones 6.1 Sensitivity The sensitivity of the microphone is the open-circuit sensiavity as defined in IEC 1094-1, If the insert voltage technique is used to determine th sensitivity for type WS
21、1 and WS2 microphones, the appropriate ground- shield reference configuration given in IEC 1094-1 shall apply. For type WS3 the provisional ground-shield reference configuration given in annex A is recommended. NOTE - If the microphone is equipped with a protedion grid, this will influence the free-
22、fieid and diuse field sensiivies. The manufachirer shaild state whether the sensith/ity has been spede with or without grid. By definition, the pressure sensitivly of a mlcrophone does not depend on he presence or absence of a protection grid. However, the sound pressure that Is measured in a small
23、cavity with a microphone is influenced by the microphone grid. 6.2 Effective front volume The effective front volume of the microphone is an important quantity when the microphone is calibrated with a sound calibrator (see 4.2 item d) of IEC 942) and when used in small couplers such as ear simulator
24、s. The effective front volume shall be specified as a function of frequency in the frequency range from 160 Hz to 1 o00 Hz inclusive. NOTE - Methods for deteminhg the effective front volume are given in dause E2 of annex E of IEC 1094-2 6.3 Upper limit of the dynamic range of a microphone The upper
25、limit of the dynamic range shall be stated in terms of the sound pressure level which, throughout the frequency range from 160 Hz to 1 O00 Hz, results in a total harmonic distortion of 3 %. NOTE - At present M geneMy accept1 7.0 - Fax 0181 996 7400. BSI offers members an individual updating service
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