BS-EN-20354-1993 ISO-354-1985.pdf

BRITISH STANDARD BS EN 20354:1993 ISO 354:1985 Implementing Amendment Nos. 1 and 2, not published separately Acoustics Measurement of sound absorption in a reverberation room The European Standard EN 20354:1993 has the status of a British Standard ICS 17.140.01 Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 01 05:13:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 20354:1993 This British Standard, having been prepared under the direction of the Environment and Pollution Standards Committee, was published under the authority of the Board of BSI and comes into effect on 27 February 1987 © BSI 04-1999 First published June 1963 First revision February 1987 ISBN 0 580 15640 0 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Environment and Pollution Standards Committee (EPC/-) to Technical Committee EPC/1, upon which the following bodies were represented: Association of Consulting Engineers British Broadcasting Corporation British Occupational Hygiene Society British Telecommunications plc Department of Health and Social Security Department of the Environment (Building Research Establishment) Department of Trade and Industry (Air Division) Department of Trade and Industry (National Physical Laboratory) Engineering Equipment and Materials Users Association Health and Safety Executive Incorporated Association of Architects and Surveyors Institute of Acoustics Institute of Occupational Hygienists Institute of Physics Institute of Sound and Vibration Research Institution of Civil Engineers Institution of Electronic and Radio Engineers Petroleum Industry Association Royal Institute of British Architects Society of Environmental Engineers Transmission and Distribution Association (BEAMA Limited) The following bodies were also represented in the drafting of the standard, through subcommittees and panels: Aggregate Concrete Block Association Association of Building Component Manufacturers Ltd. Autoclaved Aerated Concrete Products Association Brick Development Association British Ceramic Research Association Calcium Silicate Brick Association Limited Cement Makers Federation Concrete Society Gypsum Products Development Association Heriot-Watt University Hevac Association National Brassfoundry Association Structural Insulation Association Suspended Ceilings Association Timber Research and Development Association Amendments issued since publication Amd. No.Date of issueComments 7781September 1993 Adoption as a European Standard 9974May 1998Annex D has been added Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 01 05:13:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 20354:1993 © BSI 04-1999i Contents Page Committees responsibleInside front cover National forewordii Foreword2 0Introduction3 1Scope and field of application3 2References3 3Definitions3 4Principle4 5Apparatus4 6Test arrangement4 7Test procedure6 8Expression of results7 9Test report8 Annex A Diffusivity of the sound field in the reverberation room10 Annex B Explanatory remarks on the formulae in 8.1.2.3 and 8.1.310 Annex C Determination of repeatability10 Annex D (normative) Test specimen mountings for sound absorption tests11 Figure Assessment of reproducibility R of µS for a) sample 1 having a high absorption coefficient (µSë 1,00), and b) sample 2 having a low absorption coefficient (µSë 0,05) in all one-third octave bands9 Table 1 Maximum equivalent sound absorption areas for room volume V = 200 m34 Table 2 Requirements for temperature and relative humidity during measurements of T1 and T26 Table 3 Factor “t”11 Publications referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 01 05:13:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 20354:1993 ii © BSI 04-1999 National foreword This British Standard has been prepared by Subcommittee EH/1/6 and is the English language version of EN 20354:1993 Acoustics Measurement of sound absorption in a reverberation room, including its amendment A1:1997, published by the European Committee for Standardization (CEN). It is identical with ISO 354:1985, including its amendment 1, published by the International Organization for Standardization (ISO). Terminology and conventions. The text of the international standard has been approved as suitable for publication as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards; attention is drawn especially to the following. The comma has been used as a decimal marker. In British Standards it is current practice to use a full point on the baseline as the decimal marker. Wherever the words “International Standard” appear, referring to this standard, they should be read as “British Standard”. Textual errors. When adopting the text of the international standard, the textual errors listed below were discovered. They have been marked in the text and have been reported to ISO in a proposal to amend the text of the international standard. In the following clauses the word “should” should be read as “shall”. 6.1.2, line 1 6.2.1.2, line 1 6.2.2.2, lines 1, 7 and 9 6.2.2.3, lines 5 and 7 6.3, paragraph 1, lines 3 and 5 and paragraph 2, line 1 7.1, paragraph 1, line 4 and paragraph 4, line 1 7.2.1, paragraph 9, line 2 8.1.4, line 4 8.3, paragraph 3, line 7 and paragraph 4, line 3. In 6.3, line 3 of the note, “shall” should be read as “should”. In 8.1.4, line 1, “should generally” should be read as “shall”. Cross-references International standardsCorresponding British Standards ISO 5725-1986BS 5497 Precision of test methods Part 1:1987 Guide for the determination of repeatability and reproducibility for a standard test method (Technically equivalent) IEC 225:1966BS EN 61260:1996 Electroacoustics Octave-band and fractional-octave-band filters Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 01 05:13:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 20354:1993 © BSI 04-1999iii 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. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, the EN title page, pages 2 to 12, 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, Wed Nov 01 05:13:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv blank Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 01 05:13:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM EN 20354 June 1993 + A1 June 1997 UDC 534.62 Descriptors: Acoustics, tests, acoustic tests, acoustic measurements, sound absorption coefficient, reverberation, rooms English version Acoustics Measurement of sound absorption in a reverberation room (includes amendment A1:1997) (ISO 354:1985 + A1:1997) Acoustique Mesurage de labsorption acoustique en salle réverbérante (inclut lamendement A1:1997) (ISO 354:1985 + A1:1997) Akustik Messung der Schallabsorption im Hallraum (enthält Änderung A1:1997) (ISO 354:1985 + A1:1997) This European Standard was approved by CEN on 1993-06-14. CEN 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 CEN 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 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, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comité Européen de Normalisation Europäisches Komitee für Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels © 1993 Copyright reserved to CEN members Ref. No. EN 20354:1993 +A1:1997 E Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 01 05:13:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 20354:1993 © BSI 04-1999 2 Foreword This European Standard is the endorsement of ISO 354. Endorsement of ISO 354 was recommended by CEN/TC 126 “Acoustic properties of building products and of building”, under whose competence the European Standard will henceforth fall. 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 December 1993, and conflicting national standards shall be withdrawn at the latest by December 1993. The Standard was approved and in accordance with the CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, United Kingdom. Foreword to amendment A1 The text of the International Standard ISO 354:1985/A1:1997 has been prepared by Technical Committee ISO/TC 43, Acoustics, in collaboration with Technical Committee CEN/TC 126, Acoustics properties of building products and of buildings, the secretariat of which is held by AFNOR. 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 December 1997, and conflicting national standards shall be withdrawn at the latest by December 1997. According to CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 01 05:13:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 20354:1993 © BSI 04-19993 0 Introduction When a sound source operates in an enclosed space, the level to which reverberant sound builds up, and the subsequent decay of reverberant sound when the source is stopped, are governed by the sound-absorbing characteristics of the boundary surfaces and objects within the space. In general, the fraction of the incident sound power absorbed at a surface depends upon the angle of incidence. In order to relate the reverberation time of an auditorium, office, workshop, etc. to the noise reduction that would be effected by an absorbing treatment, a knowledge of the sound-absorbing characteristics of the surfaces, usually in the form of a suitable average over all angles of incidence, is required. Since the distribution of sound waves in typical enclosures includes a wide and largely unpredictable range of angles, it is convenient, for the purposes of standardization, to take a uniform distribution as the basic condition. If, furthermore, the sound intensity is independent of location within the room, such a distribution is called a diffuse sound field, and the sounds reaching a room surface are said to be at random incidence. Measurements under reverberant conditions are necessary because, in this way, the effects of practical mounting conditions can be included. Furthermore, it is the only way to determine the sound absorption of discrete objects such as chairs, office landscaping screens, etc. The purpose of this International Standard is to promote uniformity in the methods and conditions of measurement of sound absorption in reverberation rooms, so that values determined by different laboratories agree as closely as is possible at present. In order to improve precision, it may become necessary to limit further the variability of test conditions. The sound absorption data determined by the method described may be used for design calculations. In certain cases, however, deviations between predicted and measured values of reverberation time may occur. It should be emphasized that, in order to attain the above objectives, a more diffuse sound field than the one which ordinarily exists in most rooms, auditoria, etc. is required, and certain other constraints, for example on the dimensions of the reverberation room, are necessary. 1 Scope and field of application This International Standard specifies a method of measuring the sound absorption coefficient of acoustical materials used as wall or ceiling treatments, or the equivalent sound absorption area of objects, such as furniture, persons or space absorbers, in a reverberation room. It is not intended for measuring the absorption characteristics of weakly damped resonators. The results obtained can be used for comparison purposes and for design calculation with respect to room acoustics and noise control. 2 References ISO 5725, Precision of test methods Determination of repeatability and reproducibility by inter-laboratory tests. IEC Publication 225, Octave, half-octave and third-octave band filters intended for the analysis of sounds and vibrations. 3 Definitions For the purpose of this International Standard, the following definitions apply. 3.1 reverberation time the time that would be required for the sound pressure level to decrease by 60 dB after the sound source has stopped the quantity is denoted by T and is expressed in seconds NOTEThis definition is based on the assumption that, in the ideal case, there is a linear relationship between the sound pressure level and time and that the background noise level is sufficiently low. 3.2 equivalent sound absorption area of a room the hypothetical area of a totally absorbing surface without diffraction effects which, if it were the only absorbing element in the room, would give the same reverberation time as the room under consideration for the empty reverberation room, this quantity is denoted by A1; for the reverberation room containing a test specimen, it is denoted by A2. The quantity is expressed in square metres 3.3 equivalent sound absorption area of a test specimen the difference between the equivalent sound absorption area of the reverberation room with and without the test specimen the quantity is denoted by A and is expressed in square metres Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 01 05:13:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 20354:1993 4 © BSI 04-1999 3.4 sound absorption coefficient the change in equivalent sound absorption