1、BRITISH STANDARD BS EN 61183:1995 IEC 1183:1994 Electroacoustics Random-incidence and diffuse-field calibration of sound level meters The European Standard EN61183:1994has the status of a British Standard UDC 621.396:534.86:534.84:534.6.08BSEN61183:1995 This British Standard, having been prepared un
2、der the directionof the Electrotechnical Sector Board, was published underthe authority of the Standards Board and comes intoeffect on 15November1995 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference EPL/29 Draft for comment 90/22425 DC ISBN 0 580 2457
3、8 0 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 Med
4、ical 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
5、 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. Date CommentsBSEN61183:1995 BSI 10-1999 i Contents Page Commi
6、ttees responsible Inside front cover National foreword ii Foreword 2 Text of EN 61183 3 List of references Inside back coverBSEN61183:1995 ii BSI 10-1999 National foreword This British Standard has been prepared by Technical Committee EPL/29and is the English language version of EN61183:1994, Electr
7、oacoustics Random-incidence and diffuse-field calibration of sound level meters, published by the European Committee for Electrotechnical Standardization (CENELEC). It is identical with IEC1183:1994published by the International Electrotechnical Commission (IEC). A British Standard does not purport
8、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-references Publication referred to Corresponding British Standard IEC 5
9、0(801):1994 BS 4727 Glossary of electrotechnical, power, telecommunication, electronics, lighting and colour terms Part 3 Terms particular to telecommunications and electronics Group 08:1995 Acoustics and electroacoustics EN 60651:1994 BS EN 60651:1994 Sound level meters (IEC 651:1979) EN 60804:1994
10、 BS EN 60804:1994 aSpecification for integrating-averaging sound level meters (IEC 804:1985) EN 61094-1:1994 BS EN 61094 Measurement microphones (IEC 1094-1:1992) Part 1:1995 Specifications for laboratory standard microphones a Formerly BS 6698:1986. Summary of pages This document comprises a front
11、cover, an inside front cover, pages i and ii, theEN title page, pages 2 to 16, 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.EUROPEAN STANDAR
12、D NORME EUROPENNE EUROPISCHE NORM EN 61183 August 1994 UDC 621.396:534.86:534.84:534.6.08 Descriptors: Acoustic measuring instruments, sound level meters, calibration, measurements, sound pressure, instrument sensitivity, testing conditions English version Electroacoustics Random-incidence and diffu
13、se-field calibration of sound level meters (IEC 1183:1994) Electroacoustique Etalonnage des sonomtres sous incidence alatoire et en champ diffus (CEI 1183:1994) Elektroakustik Kalibrierung von Schallpegelmessern in einem Schallfeld mit stochastischem Schalleinfall und im diffusen Schallfeld (IEC 118
14、3:1994) 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 bibliogr
15、aphical 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 o
16、f 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
17、, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels 1994 Copyright
18、reserved to CENELEC members Ref. No. EN 61183:1994EEN61183:1994 BSI 10-1999 2 Foreword The text of document 29(CO)167, as prepared by IEC Technical Committee 29, Electroacoustics, was submitted to the IEC-CENELEC parallel vote in July1993. The reference document was approved by CENELEC as EN61183on
19、8March1994. The following dates were fixed: Annexes designated “normative” are part of the body of the standard. Annexes designated “informative” are given only for information. In this standard, Annex A and Annex B are informative and Annex ZA is normative. Contents Page Foreword 2 1 Scope 3 2 Norm
20、ative references 3 3 Definitions 3 4 Calibration method based on free-field measurements 4 5 Calibration method based on diffuse-field measurements 7 Annex A (informative) Practical calibration method based on free-field measurements 8 Annex B (informative) Practical calibration method based on diff
21、use-field measurements 12 Annex ZA (normative) Other international publications quoted in this standard with the references of the relevant European publications 15 Figure 1 Reference coordinate system for random-incidence sensitivity level calibration based on free-field measurements 5 Figure 2 Ref
22、erence coordinate system for the purpose of practical measurement of random-incidence sensitivity level based on free-field measurements 6 Figure A.1 A sound level meter located with its microphone at the centre of a sphere and a reference direction for sound incidence aligned with the X-axis 8 Figu
23、re A.2 A sound level meter under test mounted on a turntable to obtain incidence of sound from different directions in the X-Y plane 9 Figure A.3 Method of simulating rotation in the X-Z plane by 90 rotation of the sound level meter under test around an axis coincident with the reference direction,
24、and then rotation around a circle in the X-Y plane as in Figure A.2 9 Table A.1 Adjustment factors K(8) for calculation of random-incidence sensitivity level with % = /2 radians (90 ) 10 Table B.1 Characteristics of a type LS2aP/LS2F microphone 14 latest date of publication of an identical national
25、standard (dop) 1995-07-01 latest date of withdrawal of conflicting national standards (dow) 1995-07-01EN61183:1994 BSI 10-1999 3 1 Scope 1.1 This International Standard describes a free-field calibration method for determining random-incidence sensitivity levels of sound level meters. Additionally,
26、the standard describes a diffuse-field calibration method for determining diffuse-field sensitivity levels. 1.2 For the purpose of this International Standard, diffuse-field sensitivity level may be used interchangeably with random-incidence sensitivity level. Selection of calibration method depends
27、 on the facility available. 1.3 Results of calibrations conducted in accordance with this standard depend upon which components of a sound level meter are exposed to the sound field. 1.4 For the purpose of this standard, a sound level meter is considered to be a conventional sound level meter, an in
28、tegrating-averaging sound level meter, or any other sound measuring system. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were
29、 valid. All normative documents are subject to revision, and parties to agreements based on this InternationalStandard are encouraged to investigate the possibility of applying the most recent editions of normative documents indicated below. Members of IEC and ISO maintain registers of currently val
30、id International Standards. IEC 50(801):1992, International Electrotechnical Vocabulary (IEV), Chapter 801: Acoustics and electroacoustics. IEC 651:1979, Sound level meters. IEC 804:1985, Integrating-averaging sound level meters. IEC 1094-1:1992, Measurement microphones Part1: Specifications for lab
31、oratory standard microphones. IEC 1260:199X, Electroacoustics Octave-band and fractional octave-band filters (in preparation). ISO 266:1975, Acoustics Preferred frequencies for measurements (revision in preparation). ISO 3741:1988, Acoustics Determination of sound power levels of noise sources Preci
32、sion methods for broad-band sources in reverberation rooms. ISO 3745:1977, Acoustics Determination of sound power levels of noise sources Precision methods for anechoic and semi-anechoic rooms. 3 Definitions 3.1 For the definitions of terms used in this International Standard, reference should be ma
33、de to IEC50(801). Certain additional terms are defined below for the purpose of this standard. 3.2 reference direction the direction of sound incidence specified by the manufacturer for testing the free-field sensitivity level and directional characteristics of a sound level meter 3.3 random inciden
34、ce sound field at a given location and for a given frequency or frequency band centered on that frequency, a sound field consisting of free sound waves arriving successively from all directions with equal probability and level 3.4 diffuse sound field at a given location and for a given frequency or
35、frequency band centred on that frequency, a sound field consisting of sound waves arriving more or less simultaneously from all directions with equal probability and levelEN61183:1994 4 BSI 10-1999 3.5 random-incidence sensitivity level in decibels, of a sound level meter, for a given frequency or f
36、requency band centred on that frequency, the time-average sound pressure level indicated by the instrument due to a random incidence sound field, minus the time-average sound pressure level at the position of the acoustical centre of the microphone, due to sound waves from the same sound source and
37、in the absence of the instrument 3.6 diffuse-field sensitivity level in decibels, of a sound level meter, for a given frequency or frequency band centred on that frequency, the time-average sound pressure level indicated by the instrument due to a diffuse sound field minus the time-average sound pre
38、ssure level of the sound field at the position of the acoustical centre of the microphone and in the absence of the instrument 3.7 free-field sensitivity level in decibels, of a sound level meter, for a given frequency or frequency band centred on that frequency, the sound pressure level indicated b
39、y the instrument due to a free sound-field incident from a specified direction minus the sound pressure level of the sound field at the position of the acoustical centre of the microphone and in the absence of the instrument 3.8 pressure sensitivity level in decibels, of a sound level meter, for a g
40、iven frequency or frequency band centred on that frequency, the sound pressure level indicated by the instrument due to a sound pressure uniformly applied over the surface of the diaphragm of the microphone minus the actual sound pressure level at the diaphragm 4 Calibration method based on free-fie
41、ld measurements 4.1 For each frequency or frequency band centred on that frequency, the random-incidence sensitivity level G RIof a sound level meter shall be calculated, in decibels, from 4.2 While G F= L rd L owill usually vary for individual sound level meters, the directivity factor * depends on
42、ly on dimensions and geometry and is therefore the same for all instruments of the same model. 4.3 For determination of the directivity factor *, consider the sound level meter located with the acoustical centre of the microphone at the origin of a reference coordinate system. The reference directio
43、n of the sound level meter coincides with the X-axis of the coordinate system. Sounds from different directions are incident on the sound level meter from a sound source located at a position on the surface of the sphere defined by a vector r from the origin; see Figure 1. 4.4 The directivity factor
44、 * is calculated from the following equation: G RI= G F 10lg * (1) where * is the directivity factor of the sound level meter and is a measure of the deviation from an ideal omni-directional response with equal sensitivity at all possible angles of sound incidence on the microphone; G F is the free-
45、field sensitivity level, in decibels, of the sound level meter for the reference direction of sound incidence and equal to L rd L o ; and where L rd is the sound pressure level, in decibels, indicated by the sound level meter when exposed to a plane progressive sound wave arriving at the microphone
46、from the reference direction of sound incidence; L o is the sound pressure level, in decibels, of the same plane progressive sound wave in the absence of the sound level meter. (2)EN61183:1994 BSI 10-1999 5 The integral is taken over all possible angles of incidence from locations over the surface o
47、f the surrounding sphere. 4.5 For the purpose of practical measurements, it is convenient to describe the position of the sound source by means of a sound incidence angle 8, measured from the X-axis, and an angle ! measured in a plane perpendicular to the X-axis as shown in Figure 2. The directivity
48、 factor * is then given by: 4.6 For a practical determination of random-incidence sensitivity level, the number of sound-incidence directions has to be limited. Sound pressure levels indicated by the sound level meter for particular directions are considered representative of directions near those s
49、elected. 4.7 Assuming the sound pressure level L (8,!) to be constant within sufficiently small increments of 8 and ! and dividing the range of angles 8 and ! into m and n equal parts such that %8 = 2;/m and %! = ;/n, respectively, equation (3) may be approximated by: where L(r) is the sound pressure level, in decibels, indicated by the sound level meter when exposed to a plane progressive wave arriving at the microphone from the direction of r; L rd is the sound pressure level, in decibels, indicated by the sound level
