SIST EN 1793-6:2013

SLOVENSKI STANDARD
oSIST prEN 1793-6:2010
01-september-2010
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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
Lärmschutzeinrichtungen an Straßen - Prüfverfahren zur Bestimmung der akustischen
Eigenschaften - Teil 6: Produktspezifische Merkmale - In-situ der Luftschalldämmung
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
Ta slovenski standard je istoveten z: prEN 1793-6
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 1793-6:2010 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN 1793-6:2010

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oSIST prEN 1793-6:2010


EUROPEAN STANDARD
DRAFT
prEN 1793-6
NORME EUROPÉENNE

EUROPÄISCHE NORM

June 2010
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 Lärmschutzeinrichtungen an Straßen - Prüfverfahren zur
d'essai pour la détermination de la performance acoustique Bestimmung der akustischen Eigenschaften - Teil 6:
- Partie 6: Caractéristiques intrinsèques - Valeurs in situ Produktspezifische Merkmale in situ der
d'isolation aux bruits aériens dans des conditions de champ Luftschalldämmung
acoustique direct
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 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.

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

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2010 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 1793-6:2010: E
worldwide for CEN national Members.

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Contents          Page
Foreword . 3
1 Scope . 5
2 Normative references . 5
3 Definitions . 5
4 Sound insulation index measurements . 9
4.1. General principle . 9
4.2. Measured quantity . 10
4.3. Test arrangement . 10
4.4. Measuring equipment . 14
4.5. Data processing . 16
4.6. Positioning of the measuring equipment . 21
4.7. Sample surface and meteorological conditions . 22
4.8. Single-number rating . 22
5 Measurement uncertainty . 23
6 Measuring procedure . 24
7 Test report . 24
Annex A (normative)  Categorization of single-number rating . 26
Annex B (informative)  Guidance note on use of the single-number rating . 27
Annex C (informative)  Measurement uncertainty . 28
Annex D (informative)  Template of test report on airborne sound insulation of road traffic noise
reducing devices . 31
Bibliography . 44

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Foreword
This document (prEN 1793-6:2010) has been prepared by Technical Committee CEN/TC 226 “Road
equipment”, the secretariat of which is held by AFNOR.
This document is currently submitted to the CEN Enquiry.
It should be read in conjunction with:

prEN 1793-1 Rev, Road traffic noise reducing devices - Test method for determining the acoustic
performance – Part 1: Intrinsic characteristics of sound absorption under diffuse sound field conditions

prEN 1793-2 Rev, 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 1793-3:1998, 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 under direct sound field
conditions

prEN 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
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 average 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 (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.
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 the present document.
NOTE – 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.
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1 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 following applications:
 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 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 for the restriction(s) shall be clearly
reported.
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.
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 1793-3:1997, Road traffic noise reducing devices - Test method for determining the acoustic performance
– Part 3: Normalized traffic noise spectrum.
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.
3 Definitions
For the purpose of this European Standard the following definitions apply.
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3.1
structural elements
those elements whose primary function is to support or hold in place acoustic elements
3.2
acoustical elements
those elements whose primary function is to provide the acoustic performance of the device
3.3
roadside exposure
the use of the product as a noise reducing device installed alongside roads
3.4
sound insulation index
the result of airborne sound insulation test described by formula (1)
3.5
reference height
a height h equal to half the height, h , of the noise reducing device under test: h = h /2 (see Figures 1 and
S B S B
2). 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
S B S
frequency limitation (see 4.5.8).
3.6
source reference plane for sound insulation 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 (see Figures 1, 3, 6 and 8)
NOTE The device under test includes both structural and acoustical elements
3.7
microphone reference plane
a 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 Figure 3, 6 and 8)
NOTE The device under test includes both structural and acoustical elements
3.8
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 placed so that its horizontal distance to the source reference plane is d = 1 m (see Figures 1, 4 and 7)
S
s
NOTE The actual dimensions of the loudspeaker used for the background research on which this European Standard
is based are : 0,40 x 0,285 x 0,285 m (length x width x height)
3.9
measurement grid for sound insulation index measurements
a vertical measurement grid constituted by nine equally spaced points. A microphone shall be placed in each
point (see Figures 2, 4, 5, 7, 8 and point 4.5).
3.10
barrier thickness for sound insulation index measurements
the distance t between the source reference plane and the microphone reference plane at a height equal to
B
the reference height h (see Figure 3)
S
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3.11
free-field measurement for sound insulation index measurements
measurement taken displacing the loudspeaker and the microphone in the free field in order to avoid to face
any nearby object, including the ground (see Figure 5)
3.12
Adrienne temporal window
the composite temporal window described in 4.5.6
3.13
background noise
noise coming from sources other than the source emitting the test signal
3.14
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)
3.15
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


Key:
1 Source reference plane
Figure 1 — (not to scale) Sketch of the loudspeaker-microphone assembly in front of the noise
reducing device under test for sound insulation index measurements. R: axis of rotation. S:
loudspeaker front panel
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(a) (b)
Figure 2 — (not to scale) (a): Measurement grid for sound insulation index measurements (receiver
side) - (b): Numbering of the measurement points


Key
1 Source reference plane
2 Microphone reference plane
Figure 3 — (not to scale) Sound source and microphone reference planes (side view)


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Figure 4 — (not to scale) Placement of the sound source and measurement grid for sound insulation
index measurement (side view) – M: 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 insulation index - S: loudspeaker front panel - M: measurement grid -
d = d + t + d , see formula (3)
T S B M
4 Sound insulation index measurements
4.1. General principle
The sound source emits a transient sound wave that travels toward the device under test and is partly
reflected, partly transmitted and partly diffracted by it. The microphone placed on the other side of the device
under test receives both the transmitted sound pressure wave travelling from the sound source through the
device under test, and the sound pressure wave diffracted by the top edge of the device under test (for the
test be meaningful the diffraction from the lateral edges should be sufficiently delayed). If the measurement is
repeated without the device under test between the loudspeaker and the microphone, the direct free-field
wave can be acquired. The power spectra of the direct wave and the transmitted wave give the basis for
calculating the sound insulation index.
The sound insulation index shall be the logarithmic average of the values measured at nine points placed on
the measurement grid (scanning points). See Figure 2 and formula (1).
The measurement must take place in a sound field free from reflections within the Adrienne temporal window.
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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 can be identified from their delay time and rejected.
4.2. Measured quantity
The expression used to compute the sound insulation index SI as a function of frequency, in one-third octave
bands, is:
n
 2 
F[]h ()t w ()t df
∑
tk tk
 ∫ 
k=1
 ∆f 
j
SI = −10⋅lg (1)
 
j
2
n⋅ F[]h()t w(t) df
 i i 
∫
∆f
 
j
 
where
h (t) is the incident reference component of the free-field impulse response;
i
h (t) is the transmitted component of the impulse response at the k-th scanning point;
t,k
w (t) is the reference free-field component time window (Adrienne temporal window);
i
w (t) is the time window (Adrienne temporal window) for the transmitted component at the k-th
tk
scanning point;
F is the symbol of the Fourier transform;
j is the index of the j-th one-third octave frequency band (between 100 Hz and 5 kHz);
∆f is the width of the j-the one-third octave frequency band;
i
n = 9 is the number of scanning points.
4.3. Test arrangement
The test method can be applied both in situ and on barriers purposely built to be tested using the method
described here. In the second case the specimen shall be built as follows (see Figure 6):
 a part, composed of acoustic elements;
 a post (if applicable for the specific noise reducing device under test);
 a part, composed of acoustic elements.
The test specimen shall be mounted and assembled in the same manner as the manufactured device is used
in practice with the same connections and seals.
The tested area is a circle having a radius of 2 m centred on the middle of the measurement grid. The sample
shall be built large enough to completely include this circle for each measurement.
NOTE For qualifying the sound insulation index of posts only, it is only necessary to have acoustic elements that
extend 2 m or more on either side of the post (see Figure 6).
NOTE If the device under test has a post separation less than 4 m, the separation between posts should be reduced
accordingly but the overall minimum width of the construction should be the same as shown in Figure 6.
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(a) (b)

                       (c)
Figure 6 — Sketch of the minimum sample required for measurements in laboratory conditions - (a):
Sound insulation index measurements for elements and posts - (b): Sound insulation index
measurements in front of a post only - (c): Sound insulation index measurements in front of a sample
having a post separation smaller than 4 m. Thin circles: tested area for elements - Dotted circles:
tested area for posts

Figure 7 — (not to scale) Sketch of the set-up for the sound insulation index measurement - Normal
incidence of sound on the sample - Transmitted component measurement in front of a flat noise
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reducing device - S: loudspeaker front panel - M: measurement grid - d = d + t + d , see formula
T S B M
(3)


(a)

(b)
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(c)

Figure 8 — (not to scale - informative) Examples of the set-up for the sound insulation index
measurement - Normal incidence of sound on the sample - (a): Transmitted component measurements
in front of a concave noise reducing device - (b): Transmitted component measurements in front of a
convex noise reducing device- S: loudspeaker front panel - (c): Transmitted component
measurements in front of an inclined noise reducing device- S: loudspeaker front panel - M:
measurement grid

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Figure 9 — Sketch representing the essential components of the measuring system
4.4. Measuring equipment
4.4.1. Components of the measuring system
The measuring equipment shall comprise: an electro-acoustic system, consisting of an electrical signal
generator, a power amplifier and a loudspeaker, a microphone with its microphone amplifier and a signal
analyser capable of performing transformations between the time domain and the frequency domain.
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NOTE 1 Part of these devices can be integrated into a frequency analyser or a personal computer equipped with
specific add-on board(s).
The essential components of the measuring system are shown in Figure 9.
The complete measuring system shall meet the requirements of at least a type 1 instrument in accordance
with IEC 61672, except for the microphone which shall meet the requirements for type 2 and have a diameter
of ½” maximum.
NOTE 2 The measurement procedure here described is based on ratios of the power spectra of signals extracted from
impulse responses sampled with the same equipment in the same place under the same conditions within a short time.
Also, a high accuracy in measuring sound levels is not of interest here. Strict requirements on the absolute accuracy of the
measurement chain are, therefore, not needed. Anyway, the requirement for a type 1 instrument is maintained for
compatibility with other European Standards. The microphones should be sufficiently small and lightweight in order to be
fixed on a frame to constitute the microphone grid without moving. Also, they should be not too expensive. For this
reasons, the microphones are allowed to meet the requirements for type 2.
4.4.2. Sound source
The electro-acoustic sound source shall meet the following characteristics:
 have a single loudspeaker driver;
 be constructed without any port, e.g. to enhance low frequency response;
 be constructed without any electrically active or passive components (such as crossovers) which can
affect the frequency response of the whole system;
 have a smooth magnitude of the frequency response without sharp irregularities throughout the
measurement frequency range, resulting in an impulse response under free-field conditions with a length
not greater than 3 ms.
4.4.3. Test signal
The electro-acoustic source shall receive an input electrical signal which is deterministic and exactly
repeatable. The input signal has to be set in order to avoid any non-linearity of the loudspeaker.
The S/N ratio is improved by repeating the same test signal and synchronously averaging the microphone
response. At least 16 averages must be kept.
NOTE This European Standard recommends the use of a MLS signal as test signal. A different test signal may be
used, e.g. sine sweep, if results can be shown to be exactly the same. This means that it must be clearly demonstrated
that:
 the generation of the test signal is deterministic and exactly repeatable;
 impulse responses are accurately sampled (without distortion) on the whole frequency range of interest (one-third
octave bands between 100 Hz and 5 kHz);
 the test method maintains a good background noise immunity, i.e. the effective S/N ratio can be made higher than
10 dB on the whole frequency range of interest within a short measurement time (no more than 5 minutes per
impulse response) ;
 the sample rate can be chosen high enough to allow an accurate correction of possible time shifts in the impulse
responses between the measurement in front of the sample and the free-field measurement due to temperature
changes;
 the test signal is easy-to-use, i.e. it can be conveniently generated and fed to the sound source using only equipment
which is available on the market.
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4.5. Data processing
4.5.1. Calibration
The measurement procedure here described is based on ratios of the power spectra of signals extracted from
impulse responses sampled with the same equipment in the same place under the same conditions. An
absolute calibration of the measurement chain with regard to the sound pressure level is therefore not
needed. It is anyway recommended to check the correct functioning of the measurement chain from the
beginning to the end of measurements.
4.5.2. Sample rate
The frequency at which the microphone response is sampled depends on the specified upper frequency limit
of the measurement and on the anti-aliasing filter type and characteristics.
The sample rate f shall have a value greater than 43 kHz.
s
NOTE Although the signal is already unambiguously defined when the Nyquist criterion is met, higher sample rates
facilitate a clear reproduction of the signal and the knowledge of the exact wave form. Therefore, with the prescribed
sample rates errors can be detected and corrected more easily, such as time shifts in the impulse responses between the
measurement in front of the sample and the free-field measurement due to temperature changes.
The sample rate must be equal to the clock rate of the signal generator.
The cut-off frequency of the anti-aliasing filter, f , shall have a value :
co
f ≤ kf (2)
co s
where k = 1/3 for the Chebyshev filter and k = 1/4 for the Butterworth and Bessel filters.
For each measurement, the sample rate, the type and the characteristics of the anti-aliasing filter shall be
clearly stated in each test report.
4.5.3. Background noise
The effective signal-to-noise ratio S/N, taking into account sample averaging, must be greater than 10 dB over
the frequency range of measurements.
NOTE Coherent detection techniques, such as the MLS cross-correlation, provide high S/N ratios.
4.5.4. Scanning technique using a single microphone
The sound source shall be position
...