1、BRITISH STANDARD BS EN ISO 11821:1997 Acoustics Measurement of the in situ sound attenuation of a removable screen The European Standard EN ISO11821:1997 has the status of a BritishStandard ICS 17.140.99BSENISO11821:1997 This BritishStandard, having been prepared under the directionof the Health and
2、 Environment Sector Board, waspublished under the authorityof the Standards Boardand comes into effect on 15October1997 BSI 03-2000 ISBN 0 580 28780 7 National foreword This BritishStandard is the English language version of EN ISO11821:1997. It is identical with ISO11821:1997. The UK participation
3、in its preparation was entrusted by Technical Committee EH/1, Acoustics, to Subcommittee EH/1/4, Machinery noise, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for c
4、hange, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this subcommittee can be obtained on request to its secretary. Cross-references Attention is drawn to the fact that CEN and CENELEC
5、 Standards normally include an annex which lists normative references to international publications with their corresponding European publications. The BritishStandards which implement these international or European publications may be found in the BSI Standards Catalogue under the section entitled
6、 “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. 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
7、with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, theEN ISO title page, page2, the ISO title page, pagesii toiv, pages1 to8 anda back cover. This standard has been updated (s
8、ee copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No. Date CommentsBSENISO11821:1997 BSI 03-2000 i Contents Page National foreword Inside front cover Foreword 2 Foreword iii T
9、ext of ISO 11821 1ii blankEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 11821 April 1997 ICS 17.140.99 Descriptors: See ISO document English version Acoustics Measurement of the in situ sound attenuation of a removable screen (ISO11821:1997) Acoustique Mesurage de lattnuation acoustique i
10、n situ dun cran amovible (ISO11821:1997) Akustik Messung der Schalldmpfung von versetzbaren Schallschirmen im Einsatzfall (ISO11821:1997) This European Standard was approved by CEN on1997-03-03. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions
11、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 CEN member. The European Standards exist in three officia
12、l versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Bel
13、gium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and UnitedKingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stas
14、sart 36, B-1050 Brussels 1997 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref.No.ENISO11821:1997EENISO11821:1997 BSI 03-2000 2 Foreword The text of the International Standard ISO11821:1997 has been prepared by Technical Committee ISO/TC43
15、“Acoustics” in collaboration with Technical Committee CEN/TC211 “Acoustics”, the secretariat of which is held by DS. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by October1997, and conflicting na
16、tional standards shall be withdrawn at the latest by October1997. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ir
17、eland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the UnitedKingdom. Endorsement notice The text of the International Standard ISO11821:1997 was approved by CEN as a European Standard without any modification.ENISO11821:1997 ii BSI 03-2000 Contents Page Foreword
18、 iii 1 Scope 1 2 Normative references 1 3 Definitions 2 4 Instrumentation 2 5 Determination of in situ sound attenuation 3 6 Uncertainty 6 7 Information to be recorded 6 8 Information to be reported 7 Annex A (informative) Bibliography 8 Figure 1 Positions of the artificial sound source if the actua
19、l sound source cannot be moved 4 Figure 2 Measurement positions in the case of measurements over an area 5 Descriptors: Acoustics, noise (sound), noise reduction, screens (partition), tests, acoustic tests, performance tests, field tests, acoustic measurements.ENISO11821:1997 BSI 03-2000 iii Forewor
20、d ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technica
21、l committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of ele
22、ctrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least75% of the member bodies casting a vote. International Standard ISO11821 was prepared
23、 by Technical Committee ISO/TC43, Acoustics, Subcommittee SC1, Noise. Annex A of this International Standard is for information only.iv blankENISO11821:1997 BSI 03-2000 1 Introduction This International Standard specifies in situ methods for the determination of the sound attenuation performance of
24、removable sound-protecting screens for industrial purposes. Ascreen is any object (e.g.panels, flexible curtains, etc.) breaking the line of sight between source and receiver; such a screen may be flat or curved. Aremovable screen is a screen that can be dismantled without the other environmental co
25、nditions being changed. The purpose of such a screen is to shield a work station or a complete work area from the noise emitted by sound source(s). Such an area can be a zone where one operator is located or a zone occupied by several operators at no fixed positions. For example, screens can be used
26、 by a maintenance unit to reduce the effect of noise at a given location, from repair work, and to reduce the noise at a work station located close to a machine or process. Related standards concern noise attenuation measurements of enclosures under in situ conditions (ISO11546-2), and sound insulat
27、ion measurements of cabins under in situ conditions (ISO11957). Other International Standards dealing with screens in other situations are ISO10053 (sound attenuation of screens for open plan offices) and ISO10847 (sound attenuation of outdoors screens). Technical information about noise reduction i
28、n workrooms can be found in ISO11690-2. 1 Scope This International Standard specifies methods for evaluating the in situ sound attenuation performance of a removable screen, either indoors or outdoors. This engineering grade method is based on an insertion loss measurement that can be carried out ei
29、ther with shielding of the actual sound source(s) or using an artificial sound source. The sound attenuation performance achieved by such a screen, as evaluated by the present International Standard, depends on: diffraction around the edges of the screen; transmission through the components of the s
30、creen; absorption of the panels of the screen, as well as in its surroundings; the room in which the screen stands if indoors. When a specific work station is to be shielded, the insitu sound attenuation value describes the effect of the screen. However, when a complete area is to be shielded, the p
31、erformance of the screen will vary depending on the positions used for measurement. Therefore, it is recommended that the maximum and minimum values of sound attenuation are given. The sound attenuation performance is determined in terms of insertion loss. When assessing the performance of a screen
32、located indoors, the room geometry and reflections from walls, ceilings and room fittings will influence the performance. As a consequence, the comparison of screen performance can only be made if the test conditions are identical. This International Standard is applicable to screens with height and
33、 length greater than1,5m. However, it may also be used for smaller screens provided that the interested parties come to an agreement on this. As environmental conditions can affect the measurements outdoors, it is recommended that measurements should be restricted to within25m of the screen. However
34、, measurements may also cover a greater distance provided that the interested parties come to an agreement on this. Differences can occur between in situ test results. Therefore, comparison of the performance of different screens can be made only on the basis of data based on the same measurement me
35、thod performed at the same location. This International Standard applies to a complete screen only and not to individual components from which it is made. Sound insulation and sound absorption for screen components (such as panel elements, doors, windows) should be measured according to other releva
36、nt standards. This International Standard is not applicable to open plan offices screens nor to outdoor barriers dealing with community noise. It is also not intended for qualification purposes. 2 Normative references The following standards contain provisions which, through reference in this text,
37、constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent edition
38、s of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. IEC651:1979, Sound level meters. ENISO11821:1997 2 BSI 03-2000 IEC804:1985, Integrating-averaging sound level meters. IEC942:1988, Sound calibrators. IEC1260:1995, Electroacousti
39、cs Octave-band and fractional-octave-band filters. 3 Definitions For the purposes of this International Standard, the following definitions apply. 3.1 screen any object that is specially designed to shield one or more specified positions in a given area from the noise of specific sound source(s) NOT
40、EExamples are panels and flexible curtains. 3.2 removable screen a screen that can be dismantled without the other environmental conditions being changed 3.3 actual sound source(s) the sound source(s) to be shielded 3.4 sound pressure level, L p ten times the logarithm to the base10 of the ratio of
41、the mean-square sound pressure of a sound to the square of the reference sound pressure204Pa. The sound pressure level is expressed in decibels 3.5 A-weighted sound pressure level, L pA sound pressure level weighted in accordance with IEC651. The A-weighted sound pressure level is expressed in decib
42、els 3.6 unscreened sound pressure level, L p1 sound pressure level measured at one position not screened from the sound source(s) without the screen in its intended position. The unscreened sound pressure level is expressed in decibels 3.7 screened sound pressure level, L p2 sound pressure level mea
43、sured at the same position as in3.6 but screened from the sound source(s) by the screen in its intended position. the screened sound pressure level is expressed in decibels 3.8 in situ sound attenuation, D p difference, in decibels, between L p1and L p2at the particular position defined in3.6, L p1a
44、nd L p2being determined in either one-third-octave or octave bands 3.9 A-weighted in situ sound attenuation, D pA difference, in decibels, between L pA1and L pA2at the position defined in3.6 when using the actual sound source(s) 3.10 directivity index, DI i difference, in decibels, between L 360(the
45、 logarithmic mean value of the sound pressure level in12positions evenly distributed on a horizontal circle surrounding the sound source) and L 30,i(thesound pressure level in position i of the twelve positions) the radius of the circle shall be approximately1,5m DI i = L 360 L 30,i NOTEThe definiti
46、on of the directivity index stated in this International Standard is in principle equivalent to the definition given in ISO140-3. However, the procedure in this International Standard is somewhat simplified by allowing the directivity index to be determined in12discrete positions in the horizontal p
47、lane instead of using “gliding averaging” in different planes as described in ISO140-3. 4 Instrumentation The instrumentation system, including the microphones and cables, shall meet the requirements for a type1 instrument as specified in IEC651 or, in the case of integrating-averaging sound level m
48、eters, the requirements for a type1 instrument as specified in IEC804. For measurements in octave or one-third-octave bands, the instrumentation system shall meet the requirements for a class1 filter as specified in IEC1260. Before and after each series of measurements, the calibration of the entire
49、 measuring system shall be verified at one or more frequencies over the frequency range of interest, using a sound calibrator with an accuracy of 0,3dB (class1 as specified in IEC942). NOTEOther calibration methods are permissible, provided that it is shown that the instrumentation system is stable during the measurements and that measurements with and without the screen are carried out using the same measurement system. When measuring outdoors, a microphone windscreen with negligible influence on the frequency response of the microphone sh
