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1、BRITISH STANDARD BS ISO 17497-1:2004 Acoustics Sound-scattering properties of surfaces Part 1: Measurement of the random-incidence scattering coefficient in a reverberation room ICS 91.120.20 ? Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:35:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI
2、 BS ISO 17497-1:2004 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 22 July 2004 BSI 22 July 2004 ISBN 0 580 44113 X National foreword This British Standard reproduces verbatim ISO 17497-1:2004 and implements it as the UK national standard.
3、The UK participation in its preparation was entrusted by Technical Committee EH/1, Acoustics, to Subcommittee EH/1/6, Building acoustics, which has the responsibility to: A list of organizations represented on this subcommittee can be obtained on request to its secretary. Cross-references The Britis
4、h Standards which implement international publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publ
5、ication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible internatio
6、nal/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the ISO title
7、 page, pages ii to v, a blank page, pages 1 to 12, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27
8、08:35:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Reference number ISO 17497-1:2004(E) OSI 4002 INTERNATIONAL STANDARD ISO 17497-1 First edition 2004-05-01 Acoustics Sound-scattering properties of surfaces Part 1: Measurement of the random-incidence scattering coefficient in a reverberation room A
9、coustique Proprits de dispersion du son par les surfaces Partie 1: Mesurage du coefficient de dispersion sous incidence alatoire en salle rverbrante BS ISO 174971:2004 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:35:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI IS-79471 O1:(4002E) DPlcs
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15、24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI IS-79471 O1:(4002E) I SO 4002 All irthgs ersedevr iii Contents Page Forewordiv Introduction v 1 Scope 1 2 Normative references . 1 3 Terms and definitions. 1 4 Principle. 2 5 Frequency range. 3 6 Test arrangement 4 6.1 Reverberation room 4 6.2 Turntable
16、and base plate 4 6.3 Test sample . 5 7 Test procedure 6 7.1 Test signals . 6 7.2 Source and receiving equipment 7 7.3 Measurement of impulse responses. 7 7.4 Temperature and relative humidity. 7 7.5 Evaluation of decay curves 7 8 Expression of results 8 8.1 Method of calculation. 8 8.2 Precision 9 8
17、.3 Presentation of results. 10 9 Test report . 10 Annex A (informative) Accuracy of the measurement results. 11 Bibliography . 12 BS ISO 174971:2004 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:35:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI IS-79471 O1:(4002E) iv I SO 4002 All irthgs
18、ersedevr Foreword 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
19、which a technical 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 al
20、l matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are
21、circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held res
22、ponsible for identifying any or all such patent rights. ISO 17497-1 was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 2, Building acoustics. ISO 17497 consists of the following parts, under the general title Acoustics Sound-scattering properties of surfaces: Part 1: Measureme
23、nt of the random-incidence scattering coefficient in a reverberation room The following part is under preparation: Part 2: Measurement of the directional diffusion coefficient in a free field BS ISO 174971:2004 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:35:24 GMT+00:00 2006, Uncontrol
24、led Copy, (c) BSI IS-79471 O1:(4002E) I SO 4002 All irthgs ersedevr v Introduction The degree of acoustic scattering from surfaces is very important in all aspects of room acoustics (e.g. in concert halls, sound studios, industrial halls and reverberation chambers). Insufficient scattering may cause
25、 strong deviations from exponential sound pressure decay. On the other hand, an approximately diffuse sound field may be obtained with highly scattering surfaces in a room. The degree of scattering in a room can be an important factor related to the acoustic quality of the room. The scattering coeff
26、icient is introduced as a new concept in this part of ISO 17497. Together with the absorption coefficient, the scattering coefficient will be useful in room acoustic calculations, simulations and prediction models. For some time it has been known that modelling of the scattering from surfaces is ver
27、y important for obtaining reliable predictions of room acoustics. This part of ISO 17497 presents a measurement method to quantify the scattering properties of a surface to replace formerly applied but not generally accepted estimation methods. The work has been coordinated with the working group of
28、 the Audio Engineering Society, AES SC-04-02 for the Characterization of Acoustical Materials. This group emphasized the development of a measurement method for the directional diffusion coefficient, which is different from (but related to) the random incidence scattering coefficient. While the scat
29、tering coefficient is a rough measure that describes the degree of scattered sound, the diffusion coefficient describes the directional uniformity of the scattering; i.e. the quality of the diffusing surface. Therefore there is a need for both concepts and they have different applications. BS ISO 17
30、4971:2004 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:35:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:35:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI INTENRATIONAL TSANDADR IS-79471 O1:(4002E) I SO 4002 All irthgs ersedevr 1 A
31、coustics Sound-scattering properties of surfaces Part 1: Measurement of the random-incidence scattering coefficient in a reverberation room 1 Scope This part of ISO 17497 specifies a method of measuring the random-incidence scattering coefficient of surfaces as caused by surface roughness. The measu
32、rements are made in a reverberation room, either in full scale or on a physical scale model. The measurement results can be used to describe how much the sound reflection from a surface deviates from a specular reflection. The results obtained can be used for comparison purposes and for design calcu
33、lations with respect to room acoustics and noise control. The method is not intended for characterizing the spatial uniformity of the scattering from a surface. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, onl
34、y the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 354, Acoustics Measurement of sound absorption in a reverberation room ISO 9613-1, Acoustics Attenuation of sound during propagation outdoors Part 1: Calculation
35、 of the absorption of sound by the atmosphere 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 354 and the following apply. 3.1 specular reflection reflection that obeys Snells law, i.e. the angle of reflection is equal to the angle of incidence NOTE
36、Specular reflection can be obtained approximately from a plane, rigid surface with dimensions much larger than the wavelength of the incident sound. 3.2 diffuse sound field sound field in which the incident sound intensity on a plane surface is equally distributed over all solid angles covering a he
37、misphere BS ISO 174971:2004 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:35:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 17497-1:2004(E) 2 I SO 4002 All irthgs ersedevr 3.3 scattering coefficient s value calculated by one minus the ratio of the specularly reflected acoustic energy
38、to the total reflected acoustic energy NOTE Theoretically, s can take values between 0 and 1, where 0 means a totally specularly reflecting surface, and 1 means a totally scattering surface. The subscript may be used to indicate the angle of incidence relative to the normal of the surface. Random in
39、cidence is understood if there is no subscript. 3.4 random-incidence scattering coefficient s value calculated by one minus the ratio of the specularly reflected acoustic energy to the total acoustic energy reflected from a surface in a diffuse sound field 3.5 random-incidence absorption coefficient
40、 s value calculated by one minus the ratio of the total reflected acoustic energy to the incident acoustic energy, on a surface in a diffuse sound field 3.6 random-incidence specular absorption coefficient spec value calculated by one minus the ratio of the specularly reflected acoustic energy to th
41、e incident acoustic energy, on a surface in a diffuse sound field NOTE This is the apparent absorption coefficient when the losses include the scattered as well as the absorbed acoustic energy. spec may take values in the range from s to 1. 3.7 physical scale ratio 1:N ratio of any linear dimension
42、in a physical scale model to the same linear dimension in full scale NOTE The wavelength of the sound used in a scale model for acoustic measurements obeys the same physical scale ratio. So, if the speed of sound is the same in the model as in full scale, the frequencies used for the model measureme
43、nts will be a factor of N times higher than those in full scale. 4 Principle The general principle of the method can best be explained by looking at the effect of reflection and scattering in the time domain. Figure 1 shows three bandpass-filtered pulses which were reflected from a corrugated surfac
44、e for different orientations of the test sample in the free field. BS ISO 174971:2004 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:35:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI IS-79471 O1:(4002E) I SO 4002 All irthgs ersedevr 3 Key p sound pressure, in pascals t time, in millisecond
45、s Figure 1 Examples of band-pass filtered impulse responses measured at three different positions of the test sample Obviously, the initial parts of the reflections are highly correlated. This coherent part is identical with the specular component of the reflection. In contrast, the later parts are
46、not in phase and depend strongly on the specific orientation. The energy in the “tail” of the reflected pulse contains the scattered part. The principle of the measurement method is to extract the specular energy from the reflected pulses. This is done by synchronized (phase-locked) averaging of the
47、 impulse responses obtained for different sample orientations. The principle can be directly applied to measurements in the reverberation room. In addition to conventional measurements of absorption coefficient, the (circular) sample is placed on a turntable and impulse responses are obtained for di
48、fferent sample orientations. By synchronized averaging of the pressure impulse responses, the specular components add up in phase, whereas the scattered sound interferes destructively. Assuming statistical independence between scattered components, it can be shown (see 1) that after synchronized add
49、ition of n room impulse responses, the initial decay is related to the combined effects of absorption and an apparent energy loss due to sound scattered from the sample. 5 Frequency range The measurements should be performed in one-third-octave bands with centre frequencies covering the frequency range from 100 Hz to 5 000 Hz. This refers to full-scale measurements. If a physical scale factor of 1:N is used, the centre frequencies sh