《ISO-TR-11690-3-1997.pdf》由会员分享，可在线阅读，更多相关《ISO-TR-11690-3-1997.pdf（41页珍藏版）》请在三一文库上搜索。
1、TECHNICAL REPORT lSO/TR 11690-3 First edition 1997-02- 15 Acoustics - Recommended practice for the design of low-noise workplaces containing machinery - Part 3: Sound propagation and noise prediction in workrooms Acoustique - Pratique recommand4e pour la conception de locaux de travail B bruit rkdui
2、t contenant des machines - Partie 3: Propagation du son et pr a=400net; p=iso; o=isocs; s=central Printed in Switzerland ii Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/11/2007 06:07:20 MDTNo reproduc
3、tion or networking permitted without license from IHS -,-,- 0 IS0 ISOmR 11690-3: 1997(E) Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out
4、 through IS0 technical committees. Each member body interested in a subject for 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. IS0 co
5、llaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. The main task of technical committees is to prepare International Standards, but in exceptional circumstances a technical committee may propose the publication of a Technic
6、al Report of one of the following types: - type 1, when the required support cannot be obtained for the publication of an International Standard, despite repeated efforts; - type 2, when the subject is still under technical development or where for any other reason there is the future but not immedi
7、ate possibility of an agreement on an International Standard; - type 3, when a technical committee has collected data of a different kind from that which is normally published as an International Standard (“state of the art”, for example). Technical Reports of types 1 and 2 are subject to review wit
8、hin three years of publication, to decice whether they can be transformed into International Standards. Technical Reports of type 3 do not necessarily have to be reviewed until the data they provide are considered to be no longer valid or useful. lSO/TR 11690-3, which is a Technical Report of type 3
9、, was prepared by Technical Committee lSO/TC 43, Acoustics, Subcommittee SC 1, Noise. IS0 11690 consists of the following parts, under the general title Acoustics - Recommended practice for the design of low-noise workplaces containing machinery - Part 1: Noise control strategies - Part 2: Noise con
10、trol measures - Part 3: Sound propagation and noise prediction in workrooms . . . III Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/11/2007 06:07:20 MDTNo reproduction or networking permitted without l
11、icense from IHS -,-,- lSO/TR 11690-3: 1997(E) Introduction This Technical Report is intended for use by all parties involved in noise reduction in workplaces and design of low-noise workplaces. The objective is: - to make them aware of what is the current technical consensus regarding sound propagat
12、ion and noise prediction in workrooms, - to aid the interaction between them within a common technical framework, - to promote the understanding of the desired noise control requirements. This Technical Report provides the connection between the emission of sound sources e.g. machines and the sound
13、pressure level at workstations caused by their operation in a workroom. Therefore, it allows an interchange of information between machine suppliers, who are responsible for noise emission values, and machine users, who require low noise immission values. A further target is the assessment of the ac
14、oustical performance of a workroom. These tasks are connected by the determination of the sound propagation descriptors of a workroom. A methodology for noise prediction in workrooms is presented and a structure is given for the classification of prediction methods according to the level of detail o
15、f input parameters. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/11/2007 06:07:20 MDTNo reproduction or networking permitted without license from IHS -,-,- TECHNICAL REPORT o IS0 ISO/TR 11690-3:1997(E
16、) Acoustics - Recommended practice for the design of low-noise workplaces containing machinery - Part 3 : Sound propagation and noise prediction in workrooms 1 Scope In this part of IS0 11690, sound propagation in a room is considered together with the prediction of sound pressure levels and of nois
17、e immission at the workplace. Details of the description of the physical phenomena involved in a noise prediction scheme are strongly dependent on the situation being considered and the way this situation is modelled (input parameters, calculation techniques). This dependency is surveyed and the met
18、hodology for noise prediction is described. Recommendations are provided concerning the use of noise prediction as an aid for noise control in workrooms. Examples of use of noise prediction methods are given in annexes A to E. 2 References References listed in IS0 11690-l should also be consulted wh
19、en using this Technical Report. 3 Definitions Definitions given in IS0 11690-l apply to this Technical Report. 4 Basic principles of sound propagation in rooms 4.1 Sound propagation descriptors A basic element for noise prediction in workrooms is the prediction of the distribution of sound pressure
20、levels caused by an omnidirectional point source. This distribution is influenced by : - the shape and the volume of the room, - the absorption of the surfaces, - the fittings. 1 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/998075
21、5100 Not for Resale, 04/11/2007 06:07:20 MDTNo reproduction or networking permitted without license from IHS -,-,- ISOmR 11690-3:1997(E) IS0 The resulting sound level distribution can be considered using a spatial sound distribution curve (see definition 3.4.11 of part 1 and figures 1 and 2 of this
22、Technical Report). The information contained in this curve can be summarized, for a given distance range, by two quantities (see definitions 3.4.12 and 3.4.13 of part 1) : - the rate of spatial decay of sound pressure level per distance doubling (DW - the excess of sound pressure level with respect
23、to a free field (DLf). The spatial sound distribution curve and these two quantities are used to describe the acoustical characteristics of a room. The sound pressure level caused by a given source is indeed smaller if DLf is low and DL2 is high (see 6.3 of part 2). Annex D shows how the acoustical
24、characteristics of a room can be described from spatial sound distribution curves. The spatial sound distribution curve is determined on a free path with no obstacle between the source and the receiver. For its measurement, see 8.4 of part 2. NOTES 1 An International Standard specific to the measure
25、ment of spatial sound distribution curves in rooms is in preparation (IS0 14257 presently at the stage of draft). 2 When sound sources (machines) with dimensions too large to be neglected are considered, the sound distribution curve may differ from that of a point source for distances less than the
26、typical dimension of the machine. 4.2 Rooms with diffuse sound fields If diffuse sound field conditions are met (see definitions 3.4.8 and 3.4.9 of part l), at a certain distance from the source, sound pressure levels are nearly constant and independent of receiver position, as shown in figure 1. Co
27、pyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/11/2007 06:07:20 MDTNo reproduction or networking permitted without license from IHS -,-,- 85 80 I5 ?O 1 2 3 4 5 - hall 15 m x 15 m x 5 m L w hall 30 m x 30
28、m x 12 m _.-_- free field IO m ISOmR 11690-3:1997(E) - distance - Figure 1 : Examples of spatial sound distribution curves for an omnidirectional point source and two rooms with different sizes, equal absorption coefficients and diffuse field. The dotted curve is the spatial sound distribution curve
29、 under total free field conditions. Lp denotes the sound pressure level at a given point when the sound power level of the source is 100 dB. The sound pressure level of the diffuse field depends only on the total sound power level of all sources in the room and on the equivalent absorption area A. I
30、n rooms with a diffuse sound field, there is a direct connection between the reverberation time and the expected spatial sound distribution curve. It is therefore also possible to qualify such rooms by their reverberation time. In this case, noise prediction is relatively simple. 3 Copyright Interna
31、tional Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/11/2007 06:07:20 MDTNo reproduction or networking permitted without license from IHS -,-,- lSO/TR 11690-3: 1997(E) D IS0 4.3 Rooms with uniform sound propagation In many wo
32、rkrooms, diffuse sound field conditions cannot be assumed e.g. because the height of the room is less than one third of the length (flat rooms). In such rooms, even far from the source, the sound field depends on the position being considered and is characterized by a spatial sound distribution curv
33、e. In many workrooms, it can be assumed that the absorption and the fitting density are similar in different parts of the room (this includes a room with an absorbing ceiling and a reflecting floor). In this case, a single spatial sound distribution curve along a free path (not close to walls or fit
34、tings) represents the sound propagation and the acoustical quality of the room. As an example, figure 2 shows two typical spatial sound distribution curves flat room containing fittings. 85 80 75 30 10 m - - - -r in a - with fittings, with reflecting ceiling I w with fittings, with absorbing ceiling
35、 m-.-v. free field distance - Figure 2 : Examples of typical spatial sound distribution curves for the same flat and fitted room, with and without sound absorbing ceiling. The dotted curve is the spatial sound distribution curve under total free field conditions. Lp denotes the sound pressure level
36、at a given point when the sound power level of the source is 100 dB. 4 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/11/2007 06:07:20 MDTNo reproduction or networking permitted without license from IHS
37、 -,-,- 0 IS0 ISO/TR 11690-3: 1997(E) It is often useful to split the spatial sound distribution curve into three sections depending on the distance from the source (see 3.4.11 of part 1). The first section corresponds to the region near the source. In this region, the sound field is dominated by the
38、 direct field. The rate of spatial decay per distance doubling, DL2, is in most cases approximately 5 dB to 6 dB. Increasing the number of fittings in the vicinity of the source tends to increase the sound pressure level close to the source and to reduce it far from the source. The second section of
39、 this curve corresponds to a middle region. In this region, DL2 lies in the range 2 dB to 5 dB and DLf in the range 2 dB to 10 dB. In the far region (third part), scattering effects of fittings are important. The absorption of the walls, the density and the absorption of fittings have a dominant inf
40、luence on the sound propagation far away from the source. Therefore, in this region, DL2 may be greater than 6 dB and DLf may be negative. 4.4 Rooms with non uniform sound propagation In some situations, the room shape, absorption and fitting density differ from one part of the room to the other to
41、such an extent that it is not possible to describe the sound propagation in the room with a single spatial sound distribution curve. In such situations, it may be necessary to describe the sound field in a way which takes into account the above factors. Fittings can also be considered individually.
42、5 Noise prediction in workrooms Noise prediction in workrooms (see 9 of part 1) is an aid in making decisions regarding noise control measures. It allows calculation of the sound pressure level at any point and determination of sound propagation descriptors. It is therefore possible to compare these
43、 values with specified values or limits and to compare various solutions of a noise control programme. Although several noise prediction methods are available, all of them are based on a common procedure. This procedure is summarized in the flow chart shown in figure 3 and is outlined in the next cl
44、ause. 6 Methodology for noise prediction in workrooms Noise prediction in workrooms should follow five steps described below. 6.1 Objectives - Values to be achieved At an early stage of a noise prediction scheme, acoustical descriptors must be chosen and target values defined by the parties involved
45、, taking account of the various constraints associated with the project. Such descriptors can be sound pressure levels at workstations, immission and/or exposure data, spatial sound Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/998
46、0755100 Not for Resale, 04/11/2007 06:07:20 MDTNo reproduction or networking permitted without license from IHS -,-,- lSO/TR 11690-3:1997(E) 0 IS0 distribution curves, rates of spatial decay per distance doubling, excesses of sound pressure level, reverberation times etc. 6.2. Collection of input da
47、ta The level of detail of input parameters should be in accordance with the desired or possible value of the accuracy of the results. Different levels of detail in the description of the input parameters are shown in tables 1 to 3. The sound field that can be assumed in the room, the degree of knowl
48、edge of the input parameters and the acoustical description of the room are key factors for the selection of the prediction method. 6.2.1 Empty room description The empty room is the space limited by the room surfaces such as the boundaries of the workroom (ceiling, floor, walls) and large internal surfaces which limit the space in it (screens, partitions, enclosures, cabins, etc.). Prediction methods need the characteristics of the hall surfaces, such as their geometry (position, dimension, shape etc.), their absorption and reflection