1、Attenuation of sound during propagation outdoors Part 2: General method of calculation (IS0 9613-2 : 1996) ICs 17.140.01 DIN - IS0 9613-2 Akustik - Dmpfung des Schalls bei der Ausbreitung im Freien -Teil 2: Allgemeine Berechnungsverfahren (IS0 961 3-2 : 1996) This standard incorporates International
2、 Standard IS0 961 3-2 Acoustics - Attenuation of sound during propagation outdoors - Part 2: General method of calculation. A comma is used as the decimal marker. National foreword This standard has been prepared by ISO/TC 43. The responsible German body involved in its preparation was the Normenaus
3、schu Akusfik, Larmminderung und Schwingungsfechnik (Acoustics, Noise Control and Vibration Engineering Standards Committee). The DIN Standards corresponding to the International Standards and IEC Publications referred to in clause 2 and Annex B of the IS0 Standard are as follows: IEC Publication/ DI
4、N Standards IS0 Standard IEC 651 DIN EN 60651 IS0 1996-2 IS0 1996-3 IS0 1996-1 DIN 45645-1 DIN 18005-1, DIN 18005-2 and DIN 45645-1 DIN 18005-2 and DIN 45645-1 National Annex NA Standards referred to (and not included in Normative references and Annex B) DIN 18005-1 DIN 18005-2 DIN 45645-1 DIN EN 60
5、651 It should be noted that International Standard IS0 266 has been published in April 1997 as a full standard. Noise control in urban development - Design methods Noise control in urban development - Graphical representation of noise pollution Determination of rating level of noise exposure by meas
6、urements in the neighbourhood Sound level meters (IEC 651 : 1979 + Al : 1993) IS0 Standard comprises 18 pages. Q No pari of this standard may be reproduced without the prior permission of Ref. No. DIN IS0 961 3-2 : 1999-1 O DIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, D-10772
7、Berlin, has the exclusive right of sale for German Standards (DIN-Normen). English price group 11 Sales No. 04 11 03.00 Page 1 IS0 9613-2 : 1996 Acoustics Part 2: General method of calculation Attenuation of sound during propagation outdoors Foreword IS0 (the International Organization for Standardi
8、zation) is a worldwide fed- eration of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 technical committees. Each member body interested in a subject for which a technical committee has been established has the right to
9、 be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. IS0 collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft Internationa
10、l Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 YO of the member bodies casting a vote. International Standard IS0 961 3-2 was prepared by Technical Committee ISOTTC 43, Acoustic
11、s, Subcommittee SC 1, Noise. IS0 9613 consists of the following parts, under the general title Acous- tics - Attenuation of sound during propagation outdoors: - - Part 1: Calculation of the absorption of sound by the atmosphere Part 2: General method of calculation Part 1 is a detailed treatment res
12、tricted to the attenuation by atmospheric absorption processes. Part 2 is a more approximate and empirical treat- ment of a wider subject - the attenuation by all physical mechanisms. Annexes A and B of this part of IS0 9613 are for information only. Introduction The IS0 1996 series of standards spe
13、cifies methods for the description of noise outdoors in community environments. Other standards, on the other hand, specify methods for determining the sound power levels emitted by various noise sources, such as machinery and specified equipment (IS0 3740 series), or industrial plants (IS0 8297). T
14、his part of IS0 961 3 is intended to bridge the gap between these two types of standard, to en- able noise levels in the community to be predicted from sources of known sound emission. The method described in this part of IS0 9613 is general in the sense that it may be applied to a wide variety of n
15、oise sources, and covers most of the major mechanisms of attenuation. There are, however, constraints on its use, which arise principally from the description of en- vironmental noise in the IS0 1996 series of standards. Page 2 IS0 9613-2 : 1996 1 Scope This part of IS0 961 3 specifies an engineerin
16、g method for calculating the attenuation of sound during propa- gation outdoors in order to predict the levels of en- vironmental noise at a distance from a variety of sources. The method predicts the equivalent continu- ous A-weighted sound pressure level (as described in parts 1 to 3 of IS0 1996)
17、under meteorological con- ditions favourable to propagation from sources of known sound emission. These conditions are for downwind propagation, as specified in 5.4.3.3 of IS0 1996-2.1 987 or, equivalently, propagation under a well-developed moderate ground- based temperature inversion, such as comm
18、only oc- curs at night. Inversion conditions over water surfaces are not covered and may result in higher sound press- ure levels than predicted from this part of IS0 9613. The method also predicts a long-term average A- weighted sound pressure level as specified in IS0 1996-1 and IS0 1996-2. The lo
19、ng-term average A- weighted sound pressure level encompasses levels for a wide variety of meteorological conditions. The method specified in this part of IS0 9613 consists specifically of octave-band algorithms (with nominal midband frequencies from 63 Hz to 8 kHz) for calculat- ing the attenuation
20、of sound which originates from a point sound source, or an assembly of point sources. The source (or sources) may be moving or stationary. Specific terms are provided in the algorithms for the following physical effects: - geometrical divergence; - atmospheric absorption; - ground effect; - reflecti
21、on from surfaces; - screening by obstacles. Additional information concerning propagation through housing, foliage and industrial sites is given in an- nex A. This method is applicable in practice to a great variety of noise sources and environments. It is applicable, directly or indirectly, to most
22、 situations concerning road or rail traffic, industrial noise sources, construc- tion activities, and many other ground-based noise sources. It does not apply to sound from aircraft in flight, or to blast waves from mining, military or similar oDerations. To apply the method of this part of IS0 9613
23、, several parameters need to be known with respect to the ge- ometry of the source and of the environment, the ground surface characteristics, and the source strength in terms of octave-band sound power levels for directions relevant to the propagation NOTE 1 If only A-weighted sound power levels of
24、 the sources are known, the attenuation terms for 500 Hz may be used to estimate the resulting attenuation The accuracy of the method and the limitations to its use in practice are described in clause 9 2 Normative references The following standards contain provisions which, through reference in thi
25、s text, constitute provisions of this part of IS0 9613. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of IS0 9613 are encouraged to investigate the possibility of applying the most recent editions of
26、 the standards indicated below. Members of IEC and IS0 maintain registers of currently valid International Stan- dards. IS0 1996-1 : 1982, Acoustics - Descr/ptptlon and meas- urement of environmental noise - Part I: Basic quantities and procedures. Page 3 IS0 9613-2 : 1996 IS0 1996-2:1987, Acoustics
27、 - Description and meas- urement of environmental noise - Part 2: Acquisition of data pertinent to land use. IS0 1996-3:1987, Acoustics - Description and rneas- urement of environmental noise - Part 3: Application to noise limits. IS0 961 3-1 : 1993, Acoustics - Attenuation of sound during propagati
28、on outdoors - Part 1: Calculation of the absorption of sound by the atmosphere. IEC 651 :I 979, Sound level meters, and Amend- ment 1 : 1993. 3 Definitions For the purposes of this part of IS0 9613, the defi- nitions given in IS0 1996-1 and the following defi- nitions apply. (See table 1 for symbols
29、 and units.) 3.1 equivalent continuous A-weighted sound pressure level, LAT: Sound pressure level, in decibels, defined by equation (I): Symbol where pa(t) is the instantaneous A-weighted sound pressure, in pascals; po is the reference sound pressure = 20 x 10-6 Pa); T is a specified time interval,
30、in seconds. The A-frequency weighting is that specified for sound level meters in IEC 651. NOTEZ The time interval T should be long enough to average the effects of varying meteorological parameters. Two different situations are considered in this part of IS0 961 3, namely short-term downwind and lo
31、ng-term overall averages Table 1 - Symbols and units Definition octave-band attenuation meteorological correction distance from point source to receiver (see figure 3) distance from point source to receiver projected onto the ground plane (see figure 1) distance between source and point of reflectio
32、n on the reflecting obstacle see figure 8) distance between point of reflection on the reflecting obstacle and receiver (see figure 8) distance from source to (first) diffraction edge (see figures 6 and 7) distance from (second) diffraction edge to receiver (see figures 6 and 7) directivity index of
33、 the point sound source screening attenuation distance between the first and second diffraction edge see figure 7) ground factor mean height of source and receiver height of point source above ground (see figure 1) height of receiver above ground (see figure 1) mean height of the propagation path ab
34、ove the ground see figure 3) largest dimension of the sources minimum dimension (length or height) of the reflecting plane see figure 8) sound pressure level atmospheric attenuation coefficient angle of incidence sound reflection coefficient Unit dB dB m m m rn m m - - m - m m m m m m dB dB/km rad -
35、 Page 4 IS0 9613-2 : 1996 3.2 equivalent continuous downwind octave- band sound pressure level, LdDW): Sound pressure level, in decibels, defined by equation (2): . . . (2) where pf(r) is the instantaneous octave-band sound pressure downwind, in pascals, and the subscript f represents a nominal midb
36、and frequency of an octave- band filter. NOTE 3 The electrical characteristics of the octave-band filters should comply at least with the class 2 requirements of IEC 1260. 3.3 insertion loss (of a barrier): Difference, in deci- bels, between the sound pressure levels at a receiver in a specified pos
37、ition under two conditions: a) with the barrier removed, and b) with the barrier present (inserted), and no other significant changes that affect the propagation of sound. 4 Source description The equations to be used are for the attenuation of sound from point sources. Extended noise sources, there
38、fore, such as road and rail traffic or an industrial site (which may include several installations or plants, together with traffic moving on the site) shall be rep- resented by a set of sections (cells), each having a certain sound power and directivity. Attenuation calcu- lated for sound from a re
39、presentative point within a section is used to represent the attenuation of sound from the entire section. A line source may be divided into line sections, an area source into area sections, each represented by a point source at its centre. However, a group of point sources may be described by an eq
40、uivalent point sound source situated in the middle of the group, in particular if the sources have approximately the same strength and height above the local ground plane, the same propagation conditions exist from the sources to the point of reception, and the distance d from the single equivalent
41、point source to the receiver exceeds twice the largest dimension H, of the sources (d 2H,). If the distance d is smaller (d 6 2Hma,), or if the propagation conditions for the component point sources are different (e.g. due to screening), the total sound source shall be divided into its component poi
42、nt sources. NOTE 4 In addition to the real sources described above, image sources will be introduced to describe the reflection of sound from walls and ceilings (but not by the ground, as described in 7.5. 5 Meteorological conditions Downwind propagation conditions for the method specified in this p
43、art of IS0 9613 are as specified in 5.4.3.3 of IS0 1996-2:1987, namely wind direction within an angle of $: 45“ of the di- rection connecting the centre of the dominant sound source and the centre of the specified re- ceiver region, with the wind blowing from source to receiver, and wind speed betwe
44、en approximately 1 m/s and 5 m/s, measured at a height of 3 m to 11 m above the ground. The equations for calculating the average downwind sound pressure level LAADW) in this part of IS0 9613, including the equations for attenuation given in clause 7, are the average for meteorological con- ditions
45、within these limits. The term average here means the average over a short time interval, as de- fined in 3.1. These equations also hold, equivalently, for average propagation under a well-developed moderate ground- based temperature inversion, such as commonly oc- curs on clear, calm nights. 6 Basic
46、 equations The equivalent continuous downwind octave-band sound pressure level at a receiver location, LdDW), shall be calculated for each point source, and its im- age sources, and for the eight octave bands with nominal midband frequencies from 63 Hz to 8 kHz, from equation (3): where L, is the oc
47、tave-band sound power level, in decibels, produced by the point sound source relative to a reference sound power of one picowatt (1 pW); Page 5 IS0 9613-2 : 1996 point sound source, for each of their image sources, and for each octave band, as specified by equation (5): D, is the directivity correct
48、ion, in decibels, that describes the extent by which the equivalent continuous sound pressure level from the point sound source deviates in a specified di- rection from the level of an omnidirectional point sound source producing sound power level Lw; D, equals the directivity index D, of the point
49、sound source plus an index Dn that accounts for sound propagation into solid angles less than 4n steradians; for an omni- directional point sound source radiating into free space, D, = O dB; A is the octave-band attenuation, in decibels, that occurs during propagation from the point sound source to the receiver. NOTES 5 The letter symbol A (in italic type) signifies attenuation in this part of IS0 9613 except in subscripts, where it desig- nates the A-frequency weighting (in roman type) 6 Sound power levels in equation (3) may be determined from measurements, for example as descri
