Acoustics - Noise from shooting ranges - Part 3: Guidelines for sound propagation calculations (ISO 17201-3:2010)

ISO 17201-3:2010 specifies methods of predicting sound exposure levels of shooting sound for a single shot at a given reception point. Guidelines are given to calculate other acoustic indices from the sound exposure level. The prediction is based on the angular source energy distribution of the muzzle blast as defined in ISO 17201-1 or calculated using values from ISO 17201-2.
ISO 17201-3:2010 applies to weapons with calibres of less than 20 mm or explosive charges of less than 50 g TNT equivalent, including the projectile sound, and is applicable at distances where peak pressures are less than 1 kPa (154 dB).
NOTE National or other regulations, which could be more stringent, can apply.

Akustik - Geräusche von Schießplätzen - Teil 3: Anleitung für die Berechnung der Schallausbreitung (ISO 17201-3:2010)

Dieser Teil von ISO 17201 legt Verfahren für die Prognose des Expositionspegels des Schießgeräusches
eines Schusses an einem gegebenen Immissionsort fest. Anleitungen werden gegeben, wie andere
akustische Indizes über den Expositionspegel berechnet werden können. Die Prognose beruht auf der nach
ISO 17201-1 gemessenen oder auf der nach ISO 17201-2 berechneten winkelabhängigen Quellenenergieverteilung
des Mündungsknalls.
Dieser Teil von ISO 17201 ist anwendbar für Waffen mit einem Kaliber kleiner als 20 mm, für Treibladungen
von weniger als 50 g TNT-Äquivalent, für Entfernungen, wo die Spitzendrücke, einschließlich der Beitrag vom
Geschossknalls,kleiner als 1 kPa (154 dB) sind.
ANMERKUNG Nationale oder andere Regelwerke, die noch stringenter sein könnten, können angewendet werden.

Acoustique - Bruit des stands de tir - Partie 3: Lignes directrices pour le calcul de la propagation du son (ISO 17201-3:2010)

L'ISO 17201-3:2010 spécifie des méthodes pour prédire les niveaux d'exposition sonore pour un tir individuel en un point de réception donné. Des lignes directrices sont données pour calculer d'autres indices acoustiques à partir du niveau d'exposition sonore. La prédiction est basée sur la distribution angulaire de l'énergie acoustique émise par la détonation à la bouche, telle que définie dans l'ISO 17201-1 ou calculée au moyen des valeurs de l'ISO 17201-2.
L'ISO 17201-3:2010 couvre les armes de calibre inférieur à 20 mm ou des charges explosives de moins de 50 g d'équivalent TNT, prenant en compte le bruit du projectile à des distances où les valeurs de crête de la pression acoustique sont inférieures à 1 kPa (154 dB).

Akustika - Hrup strelskih poligonov - 3. del: Smernice za izračun širjenja zvoka (ISO 17201-3:2010)

Ta del ISO 17201 določa metode za napovedovanje stopenj zvočni izpostavljenosti strelnemu zvoku za en strel na danem sprejemnem mestu.  Smernice so podane za izračun ostalih akustičnih kazalnikov, ki izhajajo iz stopnje zvočne izpostavljenosti. Napoved je osnovana na distribuciji energije kotnega vira udara iz ustja cevi, kot je določena v ISO 17201-1 ali pa izračunana s pomočjo vrednosti iz ISO 17201-2. Ta del ISO 17201 velja za orožja s kalibri, manjšimi od 20 mm, ali eksplozivna polnjenja, manjša od ustreznih 50 g TNT, na razdaljah, kjer so konični tlaki, vključno z vložkom zvoka projektila, manjši od 1 kPa (154 dB).

General Information

Status
Withdrawn
Publication Date
31-Jan-2010
Withdrawal Date
26-Feb-2019
Technical Committee
Drafting Committee
Current Stage
9960 - Withdrawal effective - Withdrawal
Completion Date
27-Feb-2019

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Akustik - Geräusche von Schießplätzen - Teil 3: Anleitung für die Berechnung der Schallausbreitung (ISO 17201-3:2010)Acoustique - Bruit des stands de tir - Partie 3: Lignes directrices pour le calcul de la propagation du son (ISO 17201-3:2010)Acoustics - Noise from shooting ranges - Part 3: Guidelines for sound propagation calculations (ISO 17201-3:2010)97.220.10Športni objektiSports facilities95.020Vojaška tehnika. Vojaške zadeve. OrožjeMilitary engineering. Military affairs. Weapons17.140.20Emisija hrupa naprav in opremeNoise emitted by machines and equipmentICS:Ta slovenski standard je istoveten z:EN ISO 17201-3:2010SIST EN ISO 17201-3:2010en01-maj-2010SIST EN ISO 17201-3:2010SLOVENSKI

STANDARD
SIST EN ISO 17201-3:2010
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN ISO 17201-3
February 2010 ICS 97.220.10; 17.140.20; 95.020 English Version

Acoustics - Noise from shooting ranges - Part 3: Guidelines for sound propagation calculations (ISO 17201-3:2010)

Acoustique - Bruit des stands de tir - Partie 3: Lignes directrices pour le calcul de la propagation du son (ISO 17201-3:2010)

Akustik - Geräusche von Schießplätzen - Teil 3: Anleitung für die Berechnung der Schallausbreitung (ISO 17201-3:2010) This European Standard was approved by CEN on 28 November 2009.

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 CEN Management Centre 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 CEN Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre:
Avenue Marnix 17,

B-1000 Brussels © 2010 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 17201-3:2010: ESIST EN ISO 17201-3:2010

EN ISO 17201-3:2010 (E) 2 Contents Page Foreword ..............................................................................................................................................................3 SIST EN ISO 17201-3:2010

EN ISO 17201-3:2010 (E) 3 Foreword This document (EN ISO 17201-3:2010) has been prepared by Technical Committee ISO/TC 43 "Acoustics" in collaboration with Technical Committee CEN/TC 211 “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 August 2010, and conflicting national standards shall be withdrawn at the latest by August 2010. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of ISO 17201-3:2010 has been approved by CEN as a EN ISO 17201-3:2010 without any modification.

SIST EN ISO 17201-3:2010
SIST EN ISO 17201-3:2010
Reference numberISO 17201-3:2010(E)© ISO 2010

INTERNATIONAL STANDARD ISO17201-3First edition2010-02-01Acoustics — Noise from shooting ranges — Part 3: Guidelines for sound propagation calculations Acoustique — Bruit des stands de tir — Partie 3: Lignes directrices pour le calcul de la propagation du son

SIST EN ISO 17201-3:2010

ISO 17201-3:2010(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this area. Adobe is a trademark of Adobe Systems Incorporated. Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.

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ii © ISO 2010 – All rights reserved
SIST EN ISO 17201-3:2010

ISO 17201-3:2010(E) © ISO 2010 – All rights reserved iii Contents Page Foreword............................................................................................................................................................iv Introduction.........................................................................................................................................................v 1 Scope......................................................................................................................................................1 2 Normative references............................................................................................................................1 3 Terms and definitions...........................................................................................................................2 4 Source modelling..................................................................................................................................3 5 Propagation calculation........................................................................................................................4 6 Conversion of sound exposure levels................................................................................................9 7 Uncertainties........................................................................................................................................10 Annex A (normative)

Benchmark cases for shooting sheds with baffles..................................................11 Annex B (normative)

Sophisticated modelling approaches.........................................................................26 Annex C (informative)

Modelling of shooting scenarios – examples of shooting ranges........................35 Annex D (informative)

Uncertainty..................................................................................................................50 Bibliography......................................................................................................................................................54

SIST EN ISO 17201-3:2010

ISO 17201-3:2010(E) iv © ISO 2010 – All rights reserved 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 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 all 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 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 responsible for identifying any or all such patent rights. ISO 17201-3 was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 1, Noise. ISO 17201 consists of the following parts, under the general title Acoustics — Noise from shooting ranges: ⎯ Part 1: Determination of muzzle blast by measurement ⎯ Part 2: Estimation of muzzle blast and projectile sound by calculation ⎯ Part 3: Guidelines for sound propagation calculations ⎯ Part 4: Prediction of projectile sound ⎯ Part 5: Noise management

SIST EN ISO 17201-3:2010

ISO 17201-3:2010(E) © ISO 2010 – All rights reserved v Introduction The initiative to prepare a standard on impulse noise from shooting ranges was taken by the Association of European Manufacturers of Sporting Ammunition (AFEMS), in April 1996 by the submission of a formal proposal to CEN (see doc. CEN N 1085). After consultation in CEN in 1998, CEN/TC 211, Acoustics, asked ISO/TC 43, Acoustics, Subcommittee SC 1, Noise to prepare ISO 17201 (all parts). This part of ISO 17201 provides guidance for sound propagation calculation of shooting sound from shooting ranges. If calculation procedures are not implied or specified by local or national guidelines, rules and regulations, and if a more sophisticated propagation model is not available, then ISO 9613-2 may be applied, provided that the recommendations in this part of ISO 17201 are observed. The source energy of muzzle blast is typically measured or calculated for free-field conditions and often exhibits strong directivity. In many cases firearms are fired within a shooting range which has structures such as firing sheds, walls or safety barriers. Guns, particularly shotguns, are sometimes fired in many directions, e.g. in trap and skeet where the shooting direction is dictated by the flight path of the clay target. This part of ISO 17201 recommends ways in which source data can be adapted for use with ISO 9613-2 to obtain a general survey for the sound exposure levels to be expected in the neighbourhood of shooting ranges. SIST EN ISO 17201-3:2010

SIST EN ISO 17201-3:2010

INTERNATIONAL STANDARD ISO 17201-3:2010(E) © ISO 2010 – All rights reserved 1 Acoustics — Noise from shooting ranges — Part 3: Guidelines for sound propagation calculations 1 Scope This part of ISO 17201 specifies methods of predicting sound exposure levels of shooting sound for a single shot at a given reception point. Guidelines are given to calculate other acoustic indices from the sound exposure level. The prediction is based on the angular source energy distribution of the muzzle blast as defined in ISO 17201-1 or calculated using values from ISO 17201-2. This part of ISO 17201 applies to weapons with calibres of less than 20 mm or explosive charges of less than 50 g TNT equivalent, at distances where peak pressures, including the contribution from projectile sound, are less than 1 kPa (154 dB). NOTE National or other regulations, which could be more stringent, can apply. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 9613-1, Acoustics — Attenuation of sound during propagation outdoors — Part 1: Calculation of the absorption of sound by the atmosphere ISO 9613-2:1996, Acoustics — Attenuation of sound during propagation outdoors — Part 2: General method of calculation ISO 17201-1:2005, Acoustics — Noise from shooting ranges — Part 1: Determination of muzzle blast by measurement ISO 17201-2, Acoustics — Noise from shooting ranges — Part 2: Estimation of muzzle blast and projectile sound by calculation ISO 17201-4, Acoustics — Noise from shooting ranges — Part 4: Prediction of projectile sound ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in measurement (GUM:1995) IEC 61672-1, Electroacoustics — Sound level meters — Part 1: Specifications SIST EN ISO 17201-3:2010

ISO 17201-3:2010(E) 2 © ISO 2010 – All rights reserved 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 9613-2, ISO 17201-1 and the following apply. 3.1 substitute source substitute for a sound source and its firing shed by a model source without a firing shed positioned in the centre of the opening of the firing shed to represent the emission in the direction of a reception point 3.2 safety barrier 〈shooting ranges〉 barrier that is intended to stop projectiles leaving the range 3.3 safety baffle 〈shooting ranges〉 overhead barrier that is intended to stop projectiles leaving the range 3.4 firing shed structure constructed to protect the shooters and their equipment from precipitation and wind, having an opening that allows shooting at a target located on open ground 3.5 shooting range enclosed arrangement of firing positions and matching targets which, depending on the design, may include such features as a firing shed, safety barriers, safety baffles, and unsafe areas 3.6 shooting facility organizational entity consisting of one or more shooting ranges, and associated buildings and infrastructure 3.7 firing position position of the shooter within a shooting range 3.8 matching target direction direction of the shooter to the position of a moving target accounting for the time delay of the shot hitting the target 3.9 maximum A-weighted and S-weighted sound pressure level Lp,AS,max greatest A-weighted and S-weighted sound pressure level within a stated time interval NOTE 1 Maximum A-weighted and S-weighted sound pressure level is expressed in decibels. NOTE 2 A designates the frequency weighting and S the time weighting as specified in IEC 61672-1. NOTE 3 This definition is technically in accordance with ISO 1996-1:2003 [1], 3.1.2. 3.10 maximum A-weighted and F-weighted sound pressure level Lp,AF,max greatest A-weighted and F-weighted sound pressure level within a stated time interval NOTE 1 Maximum A-weighted and F-weighted sound pressure level is expressed in decibels. NOTE 2 A designates the frequency weighting and F the time weighting as specified in IEC 61672-1. NOTE 3 This definition is technically in accordance with ISO 1996-1:2003 [1], 3.1.2. SIST EN ISO 17201-3:2010

ISO 17201-3:2010(E) © ISO 2010 – All rights reserved 3 3.11 maximum A-weighted and I-weighted sound pressure level Lp,AI,max greatest A-weighted and I-weighted sound pressure level within a stated time interval NOTE 1 Maximum A-weighted and I-weighted sound pressure level is expressed in decibels. NOTE 2 A designates the frequency weighting and I the time weighting as specified in IEC 61672-1. 3.12 impact sound sound produced by the projectile hitting the target 3.13 diffraction point point on top of a barrier which provides the shortest pathlength for the sound travelling over the barrier to the reception point 4 Source modelling 4.1 Introduction The basic quantities to be used are the angular source energy distribution, Sq(α), and the angular source energy distribution level, Lq(α), as defined in ISO 17201-1. The angle between the line of fire and the line from the muzzle to the reception point is designated by α. If the gun is fired in an open air situation, Sq(α) can be used to describe the muzzle blast. For rifle shots, projectile sound has to be included (see 4.3). Substitute sources can be used for shed situations and for the incorporation of reflection and diffraction to calculate the reception levels as if it was an open field situation. Impact sound caused by the projectile hitting the target can usually be neglected. This part of ISO 17201 does not apply to projectiles containing a charge which is detonated at the target. 4.2 Muzzle blast 4.2.1 Background For the non-free-field situation (such as a shed with one opening), the propagation model of ISO 9613-2 is insufficient, and more complex propagation models and calculation procedures are needed. Annex A provides a benchmark case and a demonstration of how sophisticated sound propagation approximations (see Annex B) may be used to describe the sound emitted from such a range, based on the free-field data of the angular source energy distribution levels. The sound emission is then expressed by the angular source energy level distribution of a substitute source positioned at a representative position in front of or above the firing shed. All further calculations of the sound pressure level are carried out as specified in Clause 5 by a point source with directivity independent of the range, which may be formed by a shed, baffles and side walls, etc. 4.2.2 Open field situation If the weapon under consideration is used outside a firing shed or similar structure, use the angular source energy distribution level Lq(α) of the specific weapon/ammunition combination directly. If a shot is fired with a reflecting surface near the shooter, take the reflection into account. The directivity has to be adjusted accordingly. If the gun can be fired in varying horizontal and vertical directions, account for these directions separately. Examples of open field situations are described in Annex C. SIST EN ISO 17201-3:2010

ISO 17201-3:2010(E) 4 © ISO 2010 – All rights reserved 4.2.3 Non-open field situation 4.2.3.1 Shooting shed In this case the shot is fired in a shed (see for example Annex B). Part of the energy radiated due to the muzzle blast is absorbed by the walls and the ground. If baffles and side walls are present, take the reflections from the ground, side walls, and baffles into account (see Annex A). An absorbing ceiling within the shed can be considered to be state of the art. The remaining energy is emitted through the opening of the shed. Figure 1 depicts a shed with side walls and safety overhead baffles. Therefore, do not use free-field data directly. If no absorption occurs within the shed and at the baffles, the benchmark case is not a suitable model to describe the emitted sound energy. 4.2.3.2 More complex situations For more complex situations consisting of different shooting facilities, such as a trap and skeet range together with rifle ranges for large and small calibres, a larger number of sources and substitute sources may have to be included to adequately model the situation. These sources are considered incoherent. However, reflections are considered to be coherent, when at the reception point the time delay between the muzzle blast and its reflections is less than 3 ms. Then, they shall be modelled as one substitute source. 4.3 Projectile sound Modelling of projectile sound is specified in ISO 17201-2 and ISO 17201-4. ISO 17201-4 also gives guidelines for the calculation of the propagation of projectile sound, as far as it deviates from the propagation of other sound. This means that for the attenuation for projectile noise, Aexcess, ISO 9613-2 can also be used. The other attenuation parameters such as divergence, air absorption and non-linear attenuation are specified in ISO 17201-4. In open field situations, especially in front of the weapon when the distance to the trajectory is short, projectile sound can be a relevant source for the sound exposure level of shooting sound. If a shot is fired in a shooting range, projectile sound is in general of minor importance in the estimation of the sound exposure level at a reception point. However, if measures are taken to reduce the sound emission of the muzzle blast, projectile sound can then become a dominant factor. 5 Propagation calculation 5.1 General The propagation calculation may be performed using ray-tracing or more sophisticated models, which take specific weather conditions into account. To calculate a long-term Leq the results are weighted with respect to the frequency of occurrence of weather conditions pertinent to the time periods of interest during which the shooting range is operated. 5.2 Application of ISO 9613-2 to open field situations It should be noted that ISO 9613-2 neither applies to shooting sound, nor accounts for changes in sound pressure time history during propagation. It therefore cannot yield results for time-weighted metrics such as LF,max. ISO 9613-2 does not adequately account for meteorological effects on sound propagation over distances greater than 1 km. Furthermore, the use of ISO 9613-2 is not recommended if the spectrum at reception is dominated by frequencies below 100 Hz. However, ISO 9613-2 may be applied to model propagation of shooting sound if modifications are introduced. SIST EN ISO 17201-3:2010

ISO 17201-3:2010(E) © ISO 2010 – All rights reserved 5
a) Top view Figure 1 (continued) SIST EN ISO 17201-3:2010
ISO 17201-3:2010(E) 6 © ISO 2010 – All rights reserved
b) View in shooting direction
c) Side view

Key 1 gun/rifle 5 barrier 2 side berm 6 ground 3 roof 7 reception point 4 safety baffle

a Shooting direction. c Shielded sound. b Diffracted sound.

Figure 1 — Shooting shed situation and illustration of diffraction effects on the propagation path The sound power level and the directivity have to be substituted by the angular sound source distribution level and the ambient level by the resulting sound exposure level, LE(f), at the reception point of one specific shot under favourable sound propagation conditions. The sound exposure level for one shot fired is obtained by: divatmbargrzmisc()(,)()

11 dB(,)(,)(,)(,)(,)EqLfLfArArfArfArfArfArfα=−+−−−−− (1) where Lq(α,f) is the angular source energy distribution level, in decibels, of the weapon ammunition combination under consideration; r is the distance, in metres, from the source or substitute source P(x0,y0,z0) to the reception point P(x,y,z); α is the angle between the line of fire and the line from the source to the reception point P(x,y,z), provided that the latter line does not interfere with a barrier; f is the centre frequency, in hertz, of any frequency band; Adiv is a correction, in decibels, for the geometric spread; Aatm is the air absorption, in decibels, according to ISO 9613-1; SIST EN ISO 17201-3:2010

ISO 17201-3:2010(E) © ISO 2010 – All rights reserved 7 Abar is the shielding by barrier, in decibels, according to ISO 9613-2; Agr is the ground effect, in decibels, according to ISO 9613-2; Az is a correction for non-standard meteorological conditions {see ISO 3741 [2], ISO 3745 [3], ISO 9614-3 [4], and ISO 17201-1:2005, Equation (8)}; Amisc is a correction, in decibels, for miscellaneous other effects according to ISO 9613-2. Concerning α, if the sound is shielded by a barrier, separate calculations for each point of diffraction are necessary. The angle α used to obtain Lq(α,f) is the angle between the line of fire and the line from the source point to the point of diffraction under consideration. This approach deviates from ISO 9613-2. The insertion loss Abar is related to sound exposure level in the direction of the point of diffraction

(see example in Annex C) for the same distance between the reception point and the source point

(see Reference [6]). Concerning Agr, if ISO 9613-2:1996, 7.3.1 is applied, the ground effect is included. If ISO 9613-2:1996, 7.3.2 is applied, the reflection is taken into account by adding 3 dB to Lq(α,f) or ISO 9613-2:1996, Equation (11) is used. The calculation of Lq(x,y,z,f) for a shed opening is specified in 5.3. The long-term sound exposure level is obtained by: ,long termmetEELLC=− (2) The way to obtain Cmet depends strongly on the definition of the weather condition for which the sound exposure level LE(f) is to be calculated. If the long-term Leq is needed, take the long-term weather conditions at the site into account. If such information is not available, Cmet for the long term LA,eq can be determined according to ISO 9613-2:1996, Equation (22), using C0 = 5 dB. By application of ray-tracing models and long-term statistics of wind direction, wind speed and atmospheric stability, a more accurate value for long-term levels can be obtained (see References [7], [8]). NOTE The value 5 dB for C0 results from the assumption that favourable sound propagation conditions occur for one-third of the time. If ISO 9613-2 is applied, the following limitations should be noted. ⎯ For longer distances, ISO 9613-2 has the tendency to overestimate the long-term sound exposure level, LE,long term, during daytime (Reference [9]). ⎯ For downwind conditions, the effect of screens can be overestimated as a consequence of the induced air flow at the top of the screen (Reference [10]). ⎯ During daytime, the barrier attenuation tends to be higher compared to the value obtained by

ISO 9613-2 (see Reference [11]). ⎯ ISO 9613-2 does not consider diffraction apart from shielding. However, diffracted sound from safety baffles for example (see Figure 1) can produce a major contribution at the reception point. It should be noted that scattering is only approximately taken into account. That effect may be an important contribution to the overall level at a reception point for situations in which the sound sources are well shielded. SIST EN ISO 17201-3:2010

ISO 17201-3:2010(E) 8 © ISO 2010 – All rights reserved 5.3 Application of ISO 9613-2 for non-open field situations For the calculation of the sound immission in a non-open field situation, more sophisticated sound propagation models are needed (see 5.4). These model calculations are usually very time consuming. Even if the distance between the shooting range and the reception point is not more than a few hundred metres, the calculation over all frequencies is too long to be used for noise mapping. Therefore the concept of the substitute source is introduced to allow the use of generally available software to calculate noise maps. The sophisticated model is used to calculate the sound exposure level, LE(f), at some immission-relevant reception points, P(x,y,z), which are far enough from the shed to allow the substitution of the original source and its direct surroundings by a point source with directivity characteristics. The distance between the range and such a reception point should at least be twice the largest dimension of the range. The position of sound source energy distribution level, Lq(x,y,z,f), for this reception site and other reception sites is chosen to be in the middle of the opening through which most of the sound energy travels. For a simple shed without barriers and baffles, the source point is chosen to be in the middle of the shed opening. For ranges with a shed and barriers and baffles, the position is chosen in the centre of the first opening (see Figure B.1, point P). It should be noted that the calculated levels can also be chosen on a circle and that the angular source energy distribution level can then be calculated according to the procedures specified for measurement in

ISO 17201-1. The sound source energy distribution level of the substitute source, Lq,S(α,f) is calculated from the exposure level using Equation (3). ,Sdiv(,)(,,,)11dB()qELfLxyzfArα=−+ (3) where LE(x,y,z,f) is the sound exposure level, expressed in decibels, for frequency f at point P(x,y,z) obtained by the boundary element method (BEM) or similar (see Annex B); Adiv(r) is the correction, expressed in decibels, for geometric spread between the assumed source position and point P(x,y,z); r is the distance, in metres, between the chosen substitute source position and P(x,y,z). In this model, the substitute source replaces the original source and its direct surroundings. If only the direction of α is of interest, Equation (1) can be applied directly. If the directivity is needed, as for example in a noise map, use the process specified in ISO 17201-1. Aatm, Abar, Agr, Amisc are excluded from the calculation of Lq,S(α). Only take into account barrier effects, etc. for those barriers which are not included in the calculation using the sophisticated model. Figure 1 shows a typical shooting shed with the overhead baffles and side walls. In Annex A, the sound exposure level for a gun fired in such a shed is given. This has been calculated with the BEM over hard ground for a number of heights and positions in the surroundings. In the benchmark case, the ground reflection has been included; Aatm, Abar and Amisc have been assumed to be zero. For existing situations, it is recommended that the chosen sophisticated model be verified by measurement of the sound exposure

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