BS EN 1793-6:2012 BSI Standards Publication Road traffic noise reducing devices — Test method for determining the acoustic performance Part 6: Intrinsic characteristics — In situ values of airborne sound insulation under direct sound field conditions BRITISH STANDARD BS EN 1793-6:2012 National foreword This British Standard is the UK implementation of EN 1793-6:2012 The UK participation in its preparation was entrusted by Technical Committee B/509, Road equipment, to Subcommittee B/509/6, Fences for the attenuation of noise A list of organizations represented on this committee can be obtained on request to its secretary This publication does not purport to include all the necessary provisions of a contract Users are responsible for its correct application © The British Standards Institution 2012 Published by BSI Standards Limited 2012 ISBN 978 580 71105 ICS 17.140.30; 93.080.30 Compliance with a British Standard cannot confer immunity from legal obligations This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 November 2012 Amendments issued since publication Date Text affected BS EN 1793-6:2012 EN 1793-6 EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM November 2012 ICS 17.140.30; 93.080.30 English Version Road traffic noise reducing devices - Test method for determining the acoustic performance - Part 6: Intrinsic characteristics - In situ values of airborne sound insulation under direct sound field conditions Dispositifs de réduction du bruit du trafic routier - Méthode d'essai pour la détermination de la performance acoustique - Partie 6: Caractéristiques intrinsèques - Valeurs in situ d'isolation aux bruits aériens dans des conditions de champ acoustique direct Lärmschutzvorrichtungen an Straßen - Prüfverfahren zur Bestimmung der akustischen Eigenschaften - Teil 6: Produktspezifische Merkmale - In-situ-Werte der Luftschalldämmung in gerichteten Schallfeldern This European Standard was approved by CEN on 29 September 2012 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-CENELEC 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-CENELEC 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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels © 2012 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members Ref No EN 1793-6:2012: E BS EN 1793-6:2012 EN 1793-6:2012 (E) Contents Page Foreword 3 Introduction 4 1 Scope 7 2 Normative references 7 3 Terms and definitions 7 4 4.1 4.2 4.3 4.4 4.4.1 4.4.2 4.4.3 4.5 4.5.1 4.5.2 4.5.3 4.5.4 4.5.5 4.5.6 4.5.7 4.5.8 4.6 4.6.1 4.6.2 4.6.3 4.6.4 4.6.5 4.7 4.7.1 4.7.2 4.7.3 4.8 4.8.1 4.8.2 4.8.3 4.8.4 Sound insulation index measurements 12 General principle 12 Measured quantity 12 Test arrangement 12 Measuring equipment 18 Components of the measuring system 18 Sound source 18 Test signal 18 Data processing 19 Calibration 19 Sample rate 19 Background noise 19 Scanning technique using a single microphone 19 Scanning technique using nine microphones 20 Adrienne temporal window 21 Placement of the Adrienne temporal window 22 Low frequency limit and sample size 23 Positioning of the measuring equipment 24 Selection of the measurement positions 24 Post measurements 25 Additional measurements 25 Reflecting objects 25 Safety considerations 25 Sample surface and meteorological conditions 25 Condition of the sample surface 25 Wind 25 Air temperature 25 Single-number rating 26 General 26 Acoustic elements 26 Posts 26 Global 27 5 Measurement uncertainty 27 6 Measuring procedure 27 7 Test report 28 Annex A (normative) Categorisation of single-number rating 30 Annex B (informative) Guidance note on use of the single-number rating 31 Annex C (informative) Measurement uncertainty 32 Annex D (informative) Template of test report on airborne sound insulation of road traffic noise reducing devices 35 Bibliography 47 BS EN 1793-6:2012 EN 1793-6:2012 (E) Foreword This document (EN 1793-6:2012) has been prepared by Technical Committee CEN/TC 226 “Road equipment”, 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 May 2013, and conflicting national standards shall be withdrawn at the latest by March 2014 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 This European Standard has been prepared, under the direction of Technical Committee CEN/TC 226 “Road equipment”, by Working Group “Anti noise devices” EN 1793-6 is part of a series of documents and should be read in conjunction with the following: EN 1793-1, Road traffic noise reducing devices — Test method for determining the acoustic performance — Part 1: Intrinsic characteristics of sound absorption; EN 1793-2, Road traffic noise reducing devices — Test method for determining the acoustic performance — Part 2: Intrinsic characteristics of airborne sound insulation under diffuse sound field conditions; EN 1793-3, Road traffic noise reducing devices — Test method for determining the acoustic performance — Part 3: Normalized traffic noise spectrum; CEN/TS 1793-4, Road traffic noise reducing devices — Test method for determining the acoustic performance — Part 4: Intrinsic characteristics — In situ values of sound diffraction; CEN/TS 1793-5, Road traffic noise reducing devices — Test method for determining the acoustic performance — Part 5: Intrinsic characteristics — In situ values of sound reflection and airborne sound insulation According to the CEN/CENELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom BS EN 1793-6:2012 EN 1793-6:2012 (E) Introduction Noise reducing devices alongside roads have to provide adequate sound insulation so that sound transmitted through the device is not significant compared with the sound diffracted over the top This European Standard specifies a test method for assessing the intrinsic airborne sound insulation performance for noise reducing devices designed for roads in non-reverberant conditions It can be applied in situ, i.e where the noise reducing devices are installed The method can be applied without damaging the surface The method can be used to qualify products to be installed along roads as well as to verify the compliance of installed noise reducing devices to design specifications Regular application of the method can be used to verify the long term performance of noise reducing devices The method requires the averaging of results of measurements taken at different points behind the device under test The method is able to investigate flat and non-flat products The method uses the same principles and equipment for measuring sound reflection (see CEN/TS 1793-5) and airborne sound insulation (the present document) The measurement results of this method for airborne sound insulation are comparable but not identical with the results of the EN 1793-2 method, mainly because the present method uses a directional sound field, while the EN 1793-2 method assumes a diffuse sound field (where all angles of incidence are equally probable) The test method described in this European Standard should not be used to determine the intrinsic characteristics of airborne sound insulation for noise reducing devices to be installed in reverberant conditions, e.g inside tunnels or deep trenches or under covers For the purpose of this European Standard, reverberant conditions are defined based on the geometric envelope, e, across the road formed by the barriers, trench sides or buildings (the envelope does not include the road surface) as shown by the dashed lines in Figure Conditions are defined as being reverberant when the percentage of open space in the envelope is less than or equal to 25 %, i.e reverberant conditions occur when w/e ≤ 0,25, where e = (w+h1+h2) BS EN 1793-6:2012 EN 1793-6:2012 (E) Key Key h1: length of left barrier surface h1: length of partial cover surface envelope h2: length of right barrier surface e = w+h1 envelope, e = w+h1+h2 (a) Partial cover on both sides of the road (b) Partial cover on one side of the road Key Key h1: length of left trench side h1: length of left barrier/building h2: length of right trench side h2: length of right barrier/building envelope, e = w+h1+h2 envelope, e = w+h1+h2 (c) Deep trench (d) Tall barriers or buildings In all cases: r: road surface; w: width of open space Figure — Sketch of the reverberant condition check in four cases (not to scale) This European Standard introduces a specific quantity, called sound insulation index, to define the airborne sound insulation of a noise reducing device This quantity should not be confused with the sound reduction index used in building acoustics, sometimes also called transmission loss Research studies suggest that a very good correlation exists between data measured according to EN 1793-2 and data measured according to the method described in this document BS EN 1793-6:2012 EN 1793-6:2012 (E) This method may be used to qualify noise reducing devices for other applications, e.g to be installed along railways or nearby industrial sites In this case, the single-number ratings should be calculated using an appropriate spectrum BS EN 1793-6:2012 EN 1793-6:2012 (E) Scope This European Standard describes a test method for measuring a quantity representative of the intrinsic characteristics of airborne sound insulation for traffic noise reducing devices: the sound insulation index The test method is intended for the following applications: determination of the intrinsic characteristics of airborne sound insulation of noise reducing devices to be installed along roads, to be measured either in situ or in laboratory conditions; determination of the in situ intrinsic characteristics of airborne sound insulation of noise reducing devices in actual use; comparison of design specifications with actual performance data after the completion of the construction work; verification of the long term performance of noise reducing devices (with a repeated application of the method); interactive design process of new products, including the formulation of installation manuals The test method is not intended for the determination of the intrinsic characteristics of airborne sound insulation of noise reducing devices to be installed in reverberant conditions, e.g inside tunnels or deep trenches or under covers Results are expressed as a function of frequency in one-third octave bands, where possible, between 100 Hz and kHz If it is not possible to get valid measurement results over the whole frequency range indicated, the results need to be given in a restricted frequency range and the reasons for the restriction(s) need to be clearly reported Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application For dated references, only the edition cited applies For undated references, the latest edition of the referenced document (including any amendments) applies EN 1793-3, Road traffic noise reducing devices — Test method for determining the acoustic performance — Part 3: Normalized traffic noise spectrum IEC 61672-1:2002, Electroacoustics — Sound level meters — Part 1: Specifications Terms and definitions For the purpose of this document, the following terms and definitions apply 3.1 noise reducing device device that is designed to reduce the propagation of traffic noise away from the road environment Note to entry: This may be a noise barrier, cladding, a road cover or an added device These devices may include both acoustic and structural elements 3.2 acoustical elements elements whose primary function is to provide the acoustic performance of the device BS EN 1793-6:2012 EN 1793-6:2012 (E) 3.3 structural elements elements whose primary function is to support or hold in place acoustic elements 3.4 sound insulation index result of airborne sound insulation test described by Formula (1) 3.5 reference height height hS equal to half the height, hB, of the noise reducing device under test: hS = hB/2 (see Figures and 3) Note to entry: When the height of the device under test is greater than m and, for practical reasons, it is not advisable to have a height of the source hS = hB/2, it is possible to have hS = m, accepting the corresponding low frequency limitation (see 4.5.8) 3.6 source reference plane for sound insulation index measurements plane facing the sound source side of the noise reducing device and touching the most protruding parts of the device under test within the tested area (see Figures 2, and 9) Note to entry: The device under test includes both structural and acoustic elements 3.7 microphone reference plane plane facing the receiver side of the noise reducing device and touching the most protruding parts of the device under test within the tested area (see Figures and 9) Note to entry: The device under test includes both structural and acoustic elements 3.8 source reference position position facing the side to be exposed to noise when the device is in place, located at the reference height hS and placed so that its horizontal distance to the source reference plane is ds = m (see Figures 2, 5, and 9) Note to entry: The actual dimensions of the loudspeaker used for the background research on which this European Standard is based are: 0,40 m x 0,285 m x 0,285 m (length x width x height) 3.9 measurement grid for sound insulation index measurements vertical measurement grid constituted of nine equally spaced points Note to entry: A microphone is placed at each point (see Figures 3, 5, 6, 8, and subclause 4.5) 3.10 barrier thickness for sound insulation index measurements distance tB between the source reference plane and the microphone reference plane at a height equal to the reference height hS (see Figures 4, and 9) 3.11 free-field measurement for sound insulation index measurements measurement taken with the loudspeaker and the microphone in an acoustic free field in order to avoid reflections from any nearby object, including the ground (see Figure 6) 3.12 Adrienne temporal window composite temporal window described in 4.5.6 BS EN 1793-6:2012 EN 1793-6:2012 (E) (i) Equipment used for measurement and analysis Sound source: Manufacturer: Type: Serial number: Microphones: Manufacturers: Types: Serial numbers: Analyzer: Manufacturer: Type: Serial number: (j) Filtering and sampling Type and characteristics of the anti-aliasing filter: Sample rate: (k) Adrienne temporal window Length: (l) Test frequency range Low frequency limit: Smallest dimension of the test object: (m) Test results: see tables and graphs in D.4 (n) Measurement uncertainty Combined standard uncertainty: Expanded uncertainty: Coverage factor: Confidence level: (o) Single-number ratings The single-number rating for the airborne sound insulation amounts to: DLSI,E = _ dB for an element (p) Category: _ DLSI,P = _dB across a post Category: _ DLSI,G = _dB global Category: _ Signature of the person responsible for the measurements Name: Place, date: signature 36 BS EN 1793-6:2012 EN 1793-6:2012 (E) D.2 Test setup (example) The barrier under test is a single-leaf, reflective timber barrier constructed in two sections, each section comprising 3,0 m wide x 2,0 m high panels, supported in between steel I-section posts which are at 3,0 m centres This is representative of the construction arrangement used alongside highways The overall dimensions of the test configuration are height = 4,0 m and width = 9,0 m Figure D.1 shows the barrier viewed from the front (traffic side) Key a: upper panel (3 m wide x m high) b: lower panel (3 m wide x m high) c: I-section post Figure D.1 — General view of test barrier (from front (traffic) side) — Crosses mark measurement positions based on the post spacing of m The source is at a height of 2,0 m above the ground The prescribed measurement grid is applied midway between posts and also in front of a post (the crosses in Figure D.1 show the approximate positions of the loudspeaker/centre microphone axis) The barrier thickness at the height of measurement is 0,100 m midway between the posts and the post thickness at the height of measurement is 0,205 m There are no sound reflecting nor sound diffracting parasitic objects acting in the sample area The test situation including the loudspeaker and microphone array is shown in Figure D.2 37 BS EN 1793-6:2012 EN 1793-6:2012 (E) Figure D.2 — Test arrangement showing loudspeaker and microphone array when measuring across the panel D.3 Test object and test situation (example) Figure D.3 shows the basic composition of the single elements of this single-leaf reflective timber noise barrier Each panel of the barrier is constructed from vertical timber fence boards held in position by horizontal rails on the rear The expansion gaps in between the planks are covered on the front of the barrier by vertical cover strips The panels are 3,0 m wide and 2,0 m high The barrier is constructed in two sections On the front of the barrier, the joint between the upper and lower section is sealed by a wide horizontal cover strip The posts are steel ‘I-section’ columns with a width of 0,105 m and a depth of 0,205 m The panels are held in place between the posts by means of large timber wedges at the rear The measuring points were on the rear of the barrier on a vertical measurement grid of x points with equal horizontal and vertical distances of 0,40 m This measurement grid was located midway between the posts and in front of the centre of a post (the centre positions being approximately at the height of the joint between the upper and lower sections) 38 BS EN 1793-6:2012 EN 1793-6:2012 (E) (a) View of front of barrier (b) View of rear of the barrier Key a: upper panel b: lower panel c: main planks d: horizontal rail e: capping piece f: I-section post g: timber wedge h: vertical cover strip i: horizontal cover strip Figure D.3 — Basic composition of the single elements of the noise barrier Figure D.4 shows a typical cross-section through the barrier, including the dimensions of the different elements 39 BS EN 1793-6:2012 EN 1793-6:2012 (E) Dimensions in millimetres (a) Plan view of noise barrier (b) Cross-section through A-A Key a: fence board b: horizontal rail c: timber wedge d: cover strip e: I-section post f: horizontal cover strip at joint between upper and lower panels g: upper panel h: lower panel Figure D.4 — Cross-section through noise barrier 40 BS EN 1793-6:2012 EN 1793-6:2012 (E) D.4 Results (example) D.4.1 Part – Results for ‘element’ in tabular form Table D.2 — Template of tabular presentation of the results for the acoustic elements Third-octave band centre frequency (Hz) Particular values of sound insulation index SI for “element” for the microphone positions and the mean Particular values Logarithmic Average SI1 SI2 SI3 SI4 SI5 SI6 SI7 SI8 SI9 200 24,5 23,5 23,9 24,3 25,1 22,3 21,9 24,4 22,6 23,5 250 25,1 29,3 20,8 25,8 31,4 22,9 22,1 31,4 23,5 24,4 315 25,2 25,9 23,1 29,5 26,1 28,8 24,8 30,5 27,1 26,2 400 30,5 27,9 30,1 21,9 21,7 22,0 28,7 30,9 28,6 25,3 500 30,2 22,3 28,8 24,5 23,6 22,7 25,9 23,9 32,7 25,0 630 25,7 23,7 26,2 34,7 33,0 35,3 27,4 25,3 29,7 27,4 800 25,0 24,8 27,3 24,3 25,1 28,9 30,3 27,6 32,0 26,6 000 32,3 30,5 31,7 21,4 25,8 27,6 29,9 27,7 35,9 27,3 250 30,9 30,2 28,3 23,5 23,0 28,6 27,9 29,7 36,0 27,2 600 25,8 26,3 29,1 24,3 27,1 28,0 26,0 23,4 28,5 26,1 000 20,7 27,0 20,2 22,7 28,5 30,3 25,1 21,1 22,9 23,1 500 22,0 28,1 26,2 28,0 26,3 27,5 20,5 19,2 23,0 23,3 150 23,0 26,5 26,4 26,7 28,2 28,7 21,0 21,4 23,3 24,2 000 23,1 22,5 21,3 29,4 33,3 29,8 22,3 21,4 21,6 23,4 000 29,2 27,1 30,6 30,1 30,6 28,7 23,0 23,9 20,7 25,6 SI Single number rating of airborne sound insulation for the acoustic element, DLSI,E = 26 dB Airborne sound insulation category = D2 41 BS EN 1793-6:2012 EN 1793-6:2012 (E) D.4.2 Part – Results for ‘element’ in graphic form Figure D.5 — Results for 'element' in graphic form 42 BS EN 1793-6:2012 EN 1793-6:2012 (E) D.4.3 Part – Results for ‘post’ in tabular form Table D.3— template of tabular presentation of the results at post Third-octave band centre frequency (Hz) Particular values of sound insulation index SI for “post” for the microphone positions and the mean Particular values Logarithmic Average SI1 SI2 SI3 SI4 SI5 SI6 SI7 SI8 SI9 200 15,6 16,2 19,3 15,9 16,8 18,9 18,7 17,0 24,2 17,5 250 15,3 17,0 22,3 16,0 18,0 21,9 24,0 19,1 33,1 18,8 315 13,3 13,5 19,7 14,9 15,2 24,6 18,9 14,7 36,4 16,2 400 13,9 12,6 21,3 13,7 13,0 20,1 14,6 13,0 23,7 14,8 500 19,0 18,9 26,3 14,1 14,7 24,6 15,9 19,5 19,9 17,7 630 18,3 16,2 27,3 22,6 19,9 27,9 24,6 20,4 23,9 20,8 800 19,0 19,2 20,2 20,4 19,6 20,1 19,8 19,6 27,0 20,1 000 19,5 25,2 26,1 19,2 20,9 20,2 27,5 23,7 26,9 22,2 250 21,4 28,2 23,9 27,7 26,8 21,5 23,8 34,7 28,7 24,9 600 18,7 30,6 33,2 23,8 31,0 24,9 22,5 30,9 28,0 24,6 000 20,3 25,7 21,7 25,0 29,0 27,4 22,1 29,5 29,2 24,3 500 22,4 20,5 21,2 27,9 31,2 27,5 26,6 18,7 25,8 23,0 150 24,1 28,4 26,4 28,8 31,5 27,9 27,2 30,3 23,3 26,8 000 30,0 30,0 27,8 29,2 30,6 27,1 28,5 24,6 19,7 25,9 000 33,7 32,1 28,0 30,6 34,0 32,0 30,2 27,9 24,9 29,4 SI Single number rating of airborne sound insulation across post, DLSI,P = 21 dB Airborne sound insulation category = D2 43 BS EN 1793-6:2012 EN 1793-6:2012 (E) D.4.4 Part – Results for ‘post’ in graphic form Figure D.6 — Results for ‘post’ in graphic form 44 BS EN 1793-6:2012 EN 1793-6:2012 (E) D.4.5 Part – Results for global condition (average of ‘element’ and ‘post’) in tabular form Table D.4 — template of tabular presentation of the results for global conditions (elements + post) Third-octave band centre frequency (Hz) Particular values of sound insulation index SI for “global” condition (average of element and post) for the microphone positions and the mean Particular values Logarithmic Average SI1 SI2 SI3 SI4 SI5 SI6 SI7 SI8 SI9 200 18,1 18,5 21,0 18,3 19,2 20,3 20,0 19,3 23,3 19,5 250 17,9 19,8 21,5 18,6 20,8 22,4 22,9 21,9 26,1 20,8 315 16,0 16,3 21,1 17,8 17,9 26,2 20,9 17,6 29,6 18,8 400 16,8 15,5 23,8 16,1 15,5 20,9 17,4 15,9 25,5 17,4 500 21,7 20,3 27,4 16,7 17,2 23,5 18,5 21,2 22,7 20,0 630 20,6 18,5 26,7 25,4 22,7 30,2 25,8 22,2 25,9 23,0 800 21,0 21,2 22,4 21,9 21,5 22,6 22,4 22,0 28,8 22,2 000 22,3 27,1 28,1 20,2 22,7 22,5 28,5 25,3 29,4 24,0 250 23,9 29,1 25,6 25,1 24,5 23,7 25,4 31,5 31,0 25,9 600 20,9 27,9 30,7 24,0 28,6 26,2 23,9 25,7 28,2 25,3 000 20,5 26,3 20,9 23,7 28,7 28,6 23,3 23,5 25,0 23,7 500 22,2 22,8 23,0 27,9 28,1 27,5 22,6 18,9 24,2 23,1 150 23,5 27,3 26,4 27,6 29,5 28,3 23,1 23,9 23,3 25,3 000 25,3 24,8 23,4 29,3 31,7 28,2 24,4 22,7 20,5 24,5 000 30,9 28,9 29,1 30,3 32,0 30,0 25,3 25,5 22,3 27,1 SI Global single number rating of airborne sound insulation for the test sample, DLSI,G = 23 dB Airborne sound insulation category = D2 45 BS EN 1793-6:2012 EN 1793-6:2012 (E) D.4.6 Part – Results for global condition (average of ‘element’ and ‘post’) in graphic form Figure D.7 — Results for global condition (average of ‘element’ and ‘post’) in graphic form 46 BS EN 1793-6:2012 EN 1793-6:2012 (E) Bibliography [1] M Garai “Measurement of the sound-absorption coefficient in situ : the reflection method using periodic pseudorandom sequences of maximum length”, Applied Acoustics, 39, 119-139 (1993) [2] E Mommertz “Angle-dependent in-situ measurements of reflection coefficients using a subtraction technique”, Applied Acoustics, 46, 251-263 (1995) [3] Adrienne Research Team “Test methods for the acoustic performance of road traffic noise reducing devices - Final report”, European Commission - DGXII - SMT Project MAT1-CT94049 (1998) [4] J.-P Clairbois, J Beaumont, M Garai, G Schupp “A new in-situ method for the acoustic performance of road traffic noise reducing devices”, Proc 16th I.C.A and 135th A.S.A meeting, Seattle, U.S.A., 471-472 (1998) and J Acoust Soc Am., 103(5), Pt 2, 2801 (1998) [5] J.-P Clairbois, J Beaumont, M Garai, G Schupp “A new in-situ method for the acoustic performance of road traffic noise reducing devices”, Proc Euro-Noise ’98, Munich, Germany, 813-818 (1998) [6] M Garai, P Guidorzi “European methodology for testing the airborne sound insulation characteristics of noise barriers in situ: experimental verification and comparison with laboratory data”, J Acoust Soc Am 108(3), 1054-1067 (2000) [7] G Watts, P Morgan “Measurement of airborne sound insulation of timber noise barriers: comparison of in situ method CEN/TS 1793-5 with laboratory method EN 1793-2”, Applied Acoustics, 68, 421-436 (2007) [8] M Garai, P Guidorzi “In situ measurements of the intrinsic characteristics of the acoustic barriers installed along a new high speed railway line”, Noise Control Eng J., 56(5), 342-355 (2008) [9] M.R Schröder “Integrated-impulse method measuring sound decay without using impulses”, J Acoust Soc Am 66(2), 497-500 (1979) [10] J Borish, J.B Angell “An efficient algorithm for measuring the impulse response using pseudorandom noise”, J Audio Eng Soc 31(7), 478-488 (1983) [11] J Borish “Self-contained crosscorrelation program for maximum-length sequences”, J Audio Eng Soc 33(11), 888-891 (1985) [12] C Bleakey, R Scaife “New formulas for predicting the accuracy of acoustical measurements made in noisy environments using the averaged m-sequence correlation technique”, J Acoust Soc Am 97(2), 1329-32 (1995) [13] F.J Harris “On the use of windows for harmonic analysis with the Discrete Fourier Transform”, Proc IEEE, 66(1), 51-83 (1978) [14] EN 1793-2, Road traffic noise reducing devices — Test method for determining the acoustic performance — Part 2: Intrinsic characteristics of airborne sound insulation under diffuse sound field conditions [15] IEC 60942:2003, Electroacoustics — Sound calibrators [16] IEC 61260:1995, Electroacoustics — Octave-band and fractional-octave-band filters [17] IEC 61672-1:2002, Electroacoustics — Sound level meters — Part 1: Specifications [18] ISO/IEC Guide 98-3,Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in measurement (GUM: 1995) 47 This page deliberately left blank This page deliberately left blank NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW British Standards Institution (BSI) BSI is the national body responsible for preparing British Standards and other 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