SIST EN 1793-5:2016

SLOVENSKI STANDARD
oSIST prEN 1793-5:2014
01-julij-2014
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ODVWQRVWLGHO%LVWYHQHODVWQRVWL7HUHQVNHYUHGQRVWLRGERMD]YRND]XSRUDER
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Road Traffic Noise reducing devices - Test method for determining the acoustic
performance - Part 5: Intrinsic characteristics - In situ values of sound reflection under
direct sound field conditions
Lärmschutzvorrichtungen an Straßen - Prüfverfahren zur Bestimmung der akustischen
Eigenschaften - Teil 5: Produktspezifische Merkmale - In-situ-Werte der Schallreflexion
in gerichteten Schallfeldern
Dispositifs de réduction du bruit du trafic routier - Méthode d'essai pour la détermination
de la performance acoustique - Partie 5: Caractéristiques intrinsèques - Valeurs in situ
de réflexion acoustique dans des conditions de champ acoustique direct
Ta slovenski standard je istoveten z: prEN 1793-5
ICS:
17.140.30 Emisija hrupa transportnih Noise emitted by means of
sredstev transport
93.080.30 Cestna oprema in pomožne Road equipment and
naprave installations
oSIST prEN 1793-5:2014 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN 1793-5:2014

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oSIST prEN 1793-5:2014

EUROPEAN STANDARD
DRAFT
prEN 1793-5
NORME EUROPÉENNE

EUROPÄISCHE NORM

March 2014
ICS 17.140.30; 93.080.30
English Version
Road Traffic Noise reducing devices - Test method for
determining the acoustic performance - Part 5: Intrinsic
characteristics - In situ values of sound reflection under direct
sound field conditions
 Lärmschutzvorrichtungen an Straßen - Prüfverfahren zur
Bestimmung der akustischen Eigenschaften - Teil 5:
Produktspezifische Merkmale - In-situ-Werte der
Schallreflexion in gerichteten Schallfeldern
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee CEN/TC 226.

If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN 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.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are aware and to
provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without notice and
shall not be referred to as a European Standard.


EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2014 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 1793-5:2014 E
worldwide for CEN national Members.

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Contents
Foreword . 3
Introduction . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Symbols and abbreviations . 11
5 Sound reflection index measurements . 13
5.1 General principle. 13
5.2 Measured quantity . 13
5.3 Test arrangement . 16
5.4 Measuring equipment . 20
5.5 Data processing . 22
5.6 Positioning of the measuring equipment . 30
5.7 Sample surface and meteorological conditions . 36
5.8 Single-number rating of sound reflection DL . 37
RI
5.9 Measurement uncertainty . 37
5.10 Measuring procedure . 37
5.11 Test report . 38
Annex A (informative)  Measurement uncertainty . 40
A.1 General . 40
A.2 Measurement uncertainty based upon reproducibility data . 40
A.3 Standard deviation of repeatability and reproducibility of the sound reflection index . 40
Annex B (informative)  Template of test report on sound reflection of road noise barriers . 42
B.1 Template of test report . 42
B.2 Test setup (example) . 43
B.3 Test object and test situation (example with another product) . 45
B.4 Results (example) . 46
Annex C (informative)  Near field to far field relationship . 48
C.1 General . 48
C.2 Use of the spreadsheet . 49
Bibliography . 51

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Foreword
This document (prEN 1793-5:2014) has been prepared by Technical Committee CEN/TC 226 “Road equipment”,
the secretariat of which is held by AFNOR.
This European Standard has been prepared, under the direction of Technical Committee CEN/TC 226 “Road
equipment”, by Working Group 6 “Anti noise devices”.
This document is currently submitted to Enquiry.
It should be read in conjunction with:
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
EN 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 1793-6, 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
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Introduction
This document describes a test method for determining the intrinsic characteristics of sound reflection of noise
reducing devices designed for roads in non-reverberant conditions (a measure of intrinsic performance). 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 average of results of measurements taken in different points in front of the device under
test and/or for specific angles of incidences. The method is able to investigate flat and non-flat products.
The measurements results of this method for sound reflection are not directly comparable with the results of the
laboratory method (e.g. EN 1793-1), mainly because the present method uses a directional sound field, while the
laboratory method assumes a diffuse sound field. The test method described in the present document should not
be used to determine the intrinsic characteristics of sound reflection of noise reducing devices to be installed in
reverberant conditions, e.g. claddings inside tunnels or deep trenches.
For the purpose of this document reverberant conditions are defined based on the envelope, e, across the road
formed by the device under test, trench sides or buildings (the envelope does not include the road surface) as
shown by the dashed lines in Figure 1. Conditions are defined as being reverberant when the percentage of open
space in the envelope is less than or equal to 25 %, i.e.
+h )
Reverberant conditions occur when w/e ≤ 0,25, where e = (w+h
1 2
This method introduces a specific quantity, called reflection index, to define the sound reflection in front of a noise
reducing device, while the laboratory method gives a sound absorption coefficient. Laboratory values of the sound
absorption coefficient can be converted to conventional values of a reflection coefficient taking the complement to
one. In this case, research studies suggest that a quite good correlation exists between laboratory data, measured
according to EN 1793-1 and field data, measured according to the method described in the present document.
NOTE This method may be used to qualify noise reducing devices for other applications, e.g. to be installed nearby
industrial sites. In this case the single-number ratings should be calculated using an appropriate spectrum.
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(a) (b)


(c) (d)
Figure 1 — (not to scale) Sketch of the reverberant condition check in four cases. (a) Partial cover on both
sides of the road; envelope, e = w+h +h . (b) Partial cover on one side of the road; e = w+h . (c) Deep trench
1 2 1
envelope, e = w+h +h . (d) Tall barriers or buildings; envelope, e = w+h +h . In all cases r: road surface; w:
1 2 1 2
width of open space
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1 Scope
The present document describes a test method for measuring a quantity representative of the intrinsic
characteristics of sound reflection from road noise reducing devices: the reflection index.
The test method is intended for the following applications:
— determination of the intrinsic characteristics of sound reflection of noise reducing devices to be installed along
roads, to be measured either on typical installations alongside roads or on a relevant sample section;
— determination of the in situ intrinsic characteristics of sound reflection 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).
The test method is not intended for the following applications:
— determination of the intrinsic characteristics of sound reflection of noise reducing devices to be installed in
reverberant conditions, e.g. inside tunnels or deep trenches.
Results are expressed as a function of frequency, in one-third octave bands between 100 Hz and 5 kHz. If it is not
possible to get valid measurements results over the whole frequency range indicated, the results shall be given in a
restricted frequency range and the reasons of the restriction(s) shall be clearly reported.
2 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 1793-1, 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
EN 1793-4, Road traffic noise reducing devices - Test method for determining the acoustic performance – Part 4:
Intrinsic characteristics – In situ values of sound diffraction
EN 1793-6, 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
IEC 60942:2003, Electroacoustics – Sound calibrators
IEC 61260:1995, Electroacoustics – Octave-band and fractional-octave-band filters
IEC 61672-1:2002, Electroacoustics – Sound level meters – Part 1: Specifications
ISO/IEC Guide 98, Guide to the expression of uncertainty in measurement
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3 Terms and definitions
For the purpose of this European Standard the following definitions apply:
3.1
noise reducing device (NRD)
a noise reducing device is a device that is designed to reduce the propagation of traffic noise away from the road
environment. 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
noise barrier
noise reducing device, which obstructs the direct transmission of airborne sound emanating from road traffic
3.3
acoustic element
element whose primary function is to provide the acoustic performance of the device
3.4
structural element
element whose primary function is to support or hold in place acoustic elements
3.5
cladding
noise-reducing device, which is attached to a wall or other structure and reduces the amount of sound reflected
3.6
cover
noise-reducing device, which either spans or overhangs the highway
3.7
added device
added component that influences the acoustic performance of the original noise-reducing device (acting primarily
on the diffracted energy)
3.8
roadside exposure
the use of the product as a noise reducing device installed alongside roads
3.9
sound reflection index
the quantity, resulting from a sound reflection test, described by formula (1)
3.10
measurement grid for sound reflection index measurements
a vertical measurement grid constituted of nine equally spaced microphones in a 3x3 squared configuration
Note 1 to entry The orthogonal spacing between two subsequent microphones, either vertically or horizontally, is
s = 0,40 m.
Note 2 to entry See Figure 3 and point 5.6.
Note 3 to entry Microphones are numbered like in Figure 3.b.
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3.11
reference height
a height h equal to half the height, h , of the noise barrier under test: h = h /2
S B S B
Note 1 to entry When the height of the device under test is greater than 4 m and, for practical reasons, it is not advisable to
have a height of the source h = h /2, it is possible to have h = 2 m, accepting the corresponding low frequency limitation (see
S B S
5.5.7).
Note 2 to entry: See Figures 2 and 3.
3.12
(source and microphone) reference plane for sound reflection index measurements
a 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
Note 1 to entry See Figures 2 and 4.
3.13
source reference position
a position facing the side to be exposed to noise when the device is in place, located at the reference height h and
S
placed so that the horizontal distance of the source front panel to the reference plane is d = 1,50 m
S
Note 1 to entry See Figures 2 and 4.
3.14
measurement grid reference position
a position of the measurement grid compliant with all the following conditions: i) the measurement grid is vertical; ii)
the measurement grid is on the noise reducing device side to be exposed to noise when the device is in place; iii)
the central microphone (microphone n. 5) is located at the reference height h ; iv) the horizontal distance of the
S
central microphone to the reference plane is d = 0,25 m; v) the line passing through the centre plate of the
M
loudspeaker and the central microphone is normal to the reference plane
Note 1 to entry See Figures 2, 3 and 4.
3.15
reference loudspeaker-measurement grid distance
the distance between the front panel of the loudspeaker and the central microphone (microphone n. 5) of the
measurement grid (kept in vertical position)
Note 1 to entry the reference loudspeaker-measurement grid distance is equal to d = 1,25 m (see Figures 2 and 4)
SM
3.16
free-field measurement for sound reflection index measurements
measurement taken with the loudspeaker and the measurement grid in an acoustic free field in order to avoid
reflections from any nearby object, including the ground, keeping the same geometry as when measuring in front of
the noise reducing device under test
Note 1 to entry See Figure 5.
3.17
maximum sampled area
the surface area, projected on a front view of the noise reducing device under test for reflection index
measurements, which must remain free of reflecting objects causing parasitic reflections
3.18
Adrienne temporal window
the composite temporal window described in 5.5.5
3.19
background noise
noise coming from sources other than the sound source emitting the test signal
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3.20
signal-to-noise ratio, S/N
the difference in decibels between the level of the test signal and the level of the background noise at the moment
of detection of the useful event (within the Adrienne temporal window)
3.21
impulse response
the time signal at the output of a system when a Dirac function is applied to the input. The Dirac function, also
called δ function, is the mathematical idealisation of a signal infinitely short in time that carries a unit amount of
energy
Note 1 to entry It is impossible in practice to create and radiate true Dirac delta functions. Short transient sounds can offer
close enough approximations but are not very repeatable. An alternative measurement technique, generally more accurate, is to
use a period of deterministic, flat-spectrum signal, like maximum-length sequence (MLS) or exponential sine sweep (ESS), and
transform the measured response back to an impulse response.

Key:
1 Source and microphone reference plane 2 Reference height h [m]
S
3 Loudspeaker front panel 4 Distance between the loudspeaker front panel and the
reference plane d [m]
S
5 Distance between the loudspeaker front panel and the 6 Distance between the measurement grid and the
measurement grid d [m] reference plane d [m]
SM M
7 Measurement grid 8 Noise reducing device height h [m]
B
Figure 2 — (not to scale) Sketch of the sound source and the measurement grid in front of the noise
reducing device under test for sound reflection index measurements

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(a) (b)
Key:
1 noise reducing device height h [m] 2 Reference height h [m]
B S
3 Orthogonal spacing between two subsequent microphones s [m]
Figure 3 — (not to scale) (a): Measurement grid for sound reflection index measurements (source side) -
(b): Numbering of the measurement points as seen from the sound source


Key:
1 Source and microphone reference plane 2 Reference height h [m]
S
3 Loudspeaker front panel 4 Distance between the loudspeaker front panel and the
reference plane d [m]
S
5 Distance between the loudspeaker front panel and the 6 Distance between the measurement grid and the
measurement grid d [m] reference plane d [m]
SM M
7 Measurement grid 8 Noise reducing device height h [m]
B
Figure 4 — (not to scale) Placement of the sound source and measurement grid for sound reflection index
measurement for an inclined noise reducing device (side view)

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Key:
1 Reference height h [m] 2 Distance between the loudspeaker front panel and the measurement grid d [m]
S SM
3 Loudspeaker front panel 4 Measurement grid
Figure 5 — (not to scale) Sketch of the set-up for the reference “free-field” sound measurement for the
determination of the sound reflection index

4 Symbols and abbreviations
For the purposes of this document, the following symbols and abbreviations apply.
Table 1 – Symbols and abbreviations
Symbol or Designation Unit
abbreviation
a major axis of the ellipsoid of revolution used to define the maximum sampled area m
at oblique incidence
a , a , a , a Coefficient for the expression of the four-term full Blackman-Harris window -
0 1 2 3
b Depth of the surface structure of the sample under test m
s
b Width of a portion of material of the sample under test m
m
c Speed of sound in air m/s
C Correction factor for the geometrical divergence -
geo,k
C Correction factor for the sound source directivity -
dir,k
C Correction factor for changes in the sound source gain -
gain,k
d Horizontal distance from the source and microphone reference plane to the m
M
measurement grid; it is equal to d = 0,25 m
M
d Horizontal distance from the front panel of the loudspeaker to the source and m
S
microphone reference plane; it is equal to: d = 1,50 m
S
d Horizontal distance from the front panel of the loudspeaker to the measurement m
SM
grid; it is equal to: d = 1,25 m
SM
DL Single number rating of sound reflection dB
RI
δ Any input quantity to allow for uncertainty estimates -
i
Δf Frequency range encompassing the one-third octave frequency bands between Hz
g
500 Hz and 2 kHz
Δf Width of the j-the one-third octave frequency band Hz
j
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Δt temporal step between the discrete points of the acquired data (linked to the given ms
sample rate by Δt = 1/f )
s
Δτ moving step of the free field impulse response in the adjustment procedure included ms
in the generalized signal subtraction technique (see 5.5.4)
Δt Time delay gap between the arrival of direct sound at microphone k (k ≠ 5) and ms
k5
microphone 5
Δt Time delay gap between the arrival of direct and reflected sound at microphone k ms
k
Δd Path length difference between the arrival of direct sound at microphone k (k ≠ 5) m
k5
and microphone 5
Δd Path length difference between the arrival of direct and reflected sound at m
k
microphone k
ε Tolerance on the path length difference at microphone k m
k
F Symbol of the Fourier transform -
f Frequency Hz
f Low frequency limit of sound insulation index measurements Hz
min
f Sample rate Hz
s
f cut-off frequency of the anti-aliasing filter Hz
co
h Noise barrier height m
B
h Reference height m
S
h (t) Incident reference component of the free-field impulse response at the k-th -
ik
measurement point
h (t) Reflected component of the impulse response at the k-th measurement point -
rk
j Index of the j-th one-third octave frequency band (between 100 Hz and 5 kHz) -
k Coverage factor -
p
k Constant used for the anti-aliasing filter -
f
L Sample period length of a non-homogeneous noise reducing device m
p
n Number of measurement points on which to average -
j
r Radius of the maximum sampled area at normal incidence m
R Reduction factor dB
sub
RI Sound reflection index in the j-th one-third octave frequency band
j
s Orthogonal spacing between two subsequent microphones m
s Standard deviation of repeatability -
r
s Standard deviation of reproducibility -
R
t Time s or ms
T Length of the Blackman-Harris trailing edge of the Adrienne temporal window ms
W,BH
T Total length of the Adrienne temporal window ms
W,ADR
u Standard uncertainty -
U Expanded uncertainty -
w (t) Reference free-field component time window (Adrienne temporal window) at the k- -
ik
th measurement point
w (t) Time window (Adrienne temporal window) for the reflected component at the k-th -
rk
measurement point
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5 Sound reflection index measurements
5.1 General principle
The sound source emits a transient sound wave that travels past the measurement grid (microphone) position to
the device under test and is then reflected on it (Figures 2 and 4). Each microphone, being placed between the
sound source and the device under test, receives both the direct sound pressure wave travelling from the sound
source to the device under test and the sound pressure wave reflected (including scattering) by the device under
test. The direct sound pressure wave can be better acquired with a separate free field measurement (see Figure 5).
The power spectra of the direct and the reflected components, gives the basis for calculating the sound reflection
index.
The measurement must take place in an essentially free field in the direct surroundings of the device, i.e. a field
free from reflections coming from surfaces other than the surface of the device under test. For this reason, the
acquisition of an impulse response having peaks as sharp as possible is recommended: in this way, the reflections
coming from other surfaces than the tested device can be identified from their delay time and rejected.
5.2 Measured quantity
The expression used to compute the reflection index RI as a function of frequency, in one-third octave bands, is:
2
 
F[h (t)⋅ w (t)] df
r,k r,k
∫
n
j 
1 ∆f
j
 
RI = ⋅C ⋅C (∆f )⋅C (∆f ) (1)
j ∑ geo,k dir,k j gain,k g
2
n
k=1 
j F[h (t)⋅ w (t)] df
i,k i,k
∫
 
∆f
j
 
where
h (t) is the incident reference component of the free-field impulse response at the k-th measurement
i,k
point;
h (t) is the reflected component of the impulse response taken in front of the sample under test at the k-
r,k
th measurement point;
w (t) is the time window (Adrienne temporal window) for the incident reference component of the free-
i,k
field impulse response at the k-th measurement point;
w (t) is the time window (Adrienne temporal w
...