ISO 5128:2023

INTERNATIONAL ISO
STANDARD 5128
Second edition
2023-09
Acoustics — Measurement of interior
vehicle noise
Acoustique — Mesurage du bruit intérieur des véhicules
Reference number
© ISO 2023
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ii
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Tables of symbols and abbreviated terms . 4
5 Test equipment .6
5.1 Instrumentation for acoustic measurement . 6
5.1.1 General . 6
5.1.2 Calibration . . . 6
5.1.3 Conformity with requirements . 6
5.2 Instrumentation for vehicle speed and rotational engine speed measurements . 7
5.2.1 Vehicle speed . 7
5.2.2 Rotational engine speed (if applicable) . 7
5.3 Meteorological instrumentation . 7
5.3.1 General . 7
6 Test facility . .7
6.1 Outdoor test site . 7
6.1.1 Test track surface properties . 8
6.2 Meteorological conditions . 8
6.2.1 General . 8
6.2.2 Air temperature . 8
6.2.3 Wind . 8
6.2.4 Humidity . 8
6.3 Background noise. 8
7 Vehicle conditions . 9
7.1 General . 9
7.2 Battery state of charge . 9
7.2.1 Active sound systems . 9
7.3 Multi-mode operation . 9
7.4 Tyre conditions . . 9
7.5 Loading of the vehicle . 10
7.6 Openings, windows and auxiliaries . 11
7.7 Seat adjustment . 11
7.8 Squeak and Rattle (test equipment) . 11
8 Test procedure .11
8.1 Microphone positions . 11
8.1.1 General . 11
8.1.2 Single microphone . .12
8.1.3 Related to seats . . .12
8.1.4 Related to standing locations. 13
8.1.5 Related to sleeping-berths . 13
8.2 Test cycles . 13
8.3 Vehicle operating conditions .13
8.3.1 General .13
8.3.2 Acceleration and deceleration tests . 13
8.3.3 Steady speed test .15
8.3.4 Standstill condition . 16
8.4 Measurement readings and data processing . 16
8.4.1 General . 16
8.4.2 Measurement readings for measurements in motion . 17
iii
8.4.3 Measurement readings and data processing for the standstill condition . 17
8.5 Cycle related calculations . 17
8.5.1 Cycle specific representative sound pressure levels . 17
8.5.2 Cycle combines representative sound pressure levels . 18
8.5.3 Exposure normalization . 19
8.6 Final result . 20
8.7 Test report . 20
9 Measurement uncertainty .21
Annex A (normative) Specification on test track properties and performances .22
Annex B (informative)  .24
Annex C (informative) Considerations on the precision of this standard .26
Bibliography .32
iv
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
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO document should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use
of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed
patent rights in respect thereof. As of the date of publication of this document, ISO had not received
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expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 1, Noise.
This second edition cancels and replaces the first edition (ISO 5128:1980), which has been technically
revised.
The main changes are as follows:
— new technology neutral test method;
— updated test equipment;
— updated facility descriptions;
— new evaluation principle (instead L to L )
max A,eq
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
v
Introduction
This measurement procedure for interior vehicle noise as presented by this document has been
completely revised to better match the application needs.
The interior noise of modern vehicles has such improved, that hearing damages even under high engine
speeds and loads are unlikely. Assessments on the application of the document reveal a changed focus
on protection of drivers and passenger in a direction of long-term exposure in a sense of working place
protection.
In most countries provisions exist, which regulate the noise burden on workers on a basis of a noise
exposure over a period of 8 hours per day, a full working week over a work life of 35 years. In addition,
aspects of driver distraction and fatigue have become a stronger emphasis. In order to match this
application, it is no longer given to determine the maximum sound level from a set of measurements, as
was provided by the previous release.
The target of this edition is to determine a time average interior sound level, which is representative
for the typical driving and use of a vehicle. Therefore, in-use driving statistics were reviewed and new
in-use driving data generated by the group members. A strong focus was put on the WLTP, WHVC and
[1][2][3]
VECTO statistics which so far provides the biggest source of statistical information.
However, it should be kept in mind that the sound inside a vehicle is strongly influenced by external
factors. These factors are different for various vehicle categories. During normal driving for passenger
cars at low engine speeds and loads, the sound inside the cabin comes mainly from tyre rolling sound
transferred via structure- and air paths. The excitation of the tyre is dependent on the structure of the
surface and the characteristics of the tyre, such as the hardness of the rubber and the tyre dimension.
This standard cannot cover all eventual excitation models for smooth and rough roads or soft and hard
tyres. For reproducibility a road texture has been chosen, which is commonly used in test centre.
For heavy commercial vehicles with large cabin, wind noise can become very dominant at speeds
beyond 60 km/h. The wind direction, especially as lateral wind, can be very changeable.
The driving cycles differ strongly with regard to vehicle categories, the used speeds and accelerations
dependent on the area, where the vehicles are used. The document provides individual cycles for urban,
suburban, rural and motorway conditions, all four applicable to light duty vehicles and three of them
for heavy duty vehicles. In urban and suburban areas, the interior sound of a vehicle is a mixture of
powertrain and tyre rolling sound components. For rural and motorway conditions the influence of
powertrain is reduced but wind noise provides a stronger contribution, especially for large trucks and
buses.
The combination of the cycles is very much dependent on the typical use of a vehicle. A large variation
may exist for the same product. This document focuses on a typical use for vehicle categories, but it has
to be kept in mind, that a substantially different use, may lead to other results. A standardized data
processing for a given vehicle category will allow benchmarking of products. The availability of the
individual cycle results enables as well an estimation of the interior sound for other conditions of use.
Another important factor is the total driving time within the concept of a working day. While it appears
obvious that long haulage trucks are driven many hours per day, a delivery service in a town will have
a mix between driving and loading/unloading work. Where test results of this document are used
with regard to occupational noise exposure standards, it is essential to consider the time contribution
according to the typical use of a vehicle. Again, a large variability should be kept in mind. The test results
of this document allow as well the calculation for conditions, other than selected by this document.
All definitions in this document are based on design neutral parameters – as far as practically possible
– to enable an application for all kind of vehicle technologies, inclusive of hybrid vehicles and pure
electric vehicles.
The test procedures and calculation schemes are engineering methods and compromise between
precision, repeatability, feasibility and simplicity.
vi
INTERNATIONAL STANDARD ISO 5128:2023(E)
Acoustics — Measurement of interior vehicle noise
1 Scope
This document specifies an engineering method for measuring the interior sound of road vehicles of
categories M and N under typical driving conditions. It does not apply to agricultural tractors and field
machinery.
It specifies the conditions for obtaining reproducible and comparable measurements of sound pressure
levels inside a vehicle.
These measurements are used to obtain a representative average sound level during a typical driving
cycle to enable assessment of adverse effects on human health.
The results can be used for
— standardized assessment of interior sound for comparisons (e.g. benchmark, consumer information
programs),
— verification tests, to decide whether or not the sound inside the vehicle is in accordance with
specifications,
— regulatory purposes, for example for evaluation of sound in relation to labour or for general health
standards, and
— monitoring tests, in order to check that the sound inside the vehicles has not changed since delivery,
or between individual units of a consignment of vehicles.
This document does evaluate the exposure to interior sound of vehicles in a way as it is commonly used
for scientific effects on human health.
It does not assess maximum interior sound of a vehicle under extreme driving situations, as today’s
measured maximum sound pressure levels inside vehicles are far away from the risk to create
instantaneous hearing damages.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 10844, Acoustics — Specification of test tracks for measuring sound emitted by road vehicles and their
tyres
ISO 26101-1, Acoustics — Test methods for the qualification of the acoustic environment
ISO 13473-1, Characterization of pavement texture by use of surface profiles — Part 1: Determination of
mean profile depth
ISO 13473-3, Characterization of pavement texture by use of surface profiles — Part 3: Specification and
classification of profilometers
IEC 61672-1, Electroacoustics — Sound level meters — Part 1: Specifications
IEC 61672-3, Electroacoustics — Sound level meters — Part 3: Periodic tests
IEC 60942, Electroacoustics — Sound calibrator
ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement (GUM: 1995)
EN 13036-7, Road and airfield surface characteristics — Test methods — Part 7: Irregularity measurement
of pavement courses: the straightedge test
EN 13043, Aggregates for bituminous mixtures and surface treatments for roads, airfields and other
trafficked areas
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
Mass
3.1.1
kerb mass
mass of the vehicle, with its fuel tank(s) filled to at least 90 % of its or their capacities, including the
mass of the driver, of the fuel and liquids, fitted with the standard equipment in accordance with the
manufacturer's specifications and, when they are fitted, the mass of the bodywork, the cabin, the
coupling and the spare wheel(s) as well as the tools
[SOURCE: ISO 1176:1990, 4.6, modified — extended based on the today’s applied principles used in
regulations for sound emission of vehicles (see UN R51.03).]
3.1.2
test mass
m
t
mass of the vehicle subject to testing inclusive all equipment and payload
3.1.3
driver mass
m
d
nominal mass of a driver that shall be 75 kg (subdivided into 68 kg occupant mass at the seat and 7 kg
luggage mass)
Note 1 to entry: According to ISO 2416.
3.2
test cycle
test conditions comprising acceleration, deceleration, steady speed and standstill to establish typical
operation of a vehicle under either urban, suburban, rural or motorway condition
3.3
total power
P
n
sum of net power of all available propulsion sources
Note 1 to entry: According to ISO 1585, for vehicles with combustion engine only, P is the net power of the
n
combustion engine expressed in kilowatt.
Note 2 to entry: According to UN R85, for vehicles with electric propulsion only, P is the net power over a time
n
period of 5 minutes, expressed in kilowatt.
Note 3 to entry: According to UN R51, for vehicles with hybrid drive line, P is the sum of the net power of all
n
available propulsion sources, expressed in kilowatt.
3.4
rated engine speed
S
engine speed at which the combustion engine develops its rated maximum net power as stated by the
manufacturer
Note 1 to entry: If the rated maximum net power is reached at several engine speeds, S used in this document is
the highest engine speed at which the rated maximum net power is reached.
Note 2 to entry: ISO 80000-3 defines this term as “rated engine rotational frequency”. The term “rated engine
speed” was retained due to its common understanding by practitioners and its use in government regulations.
3.5
active sound system
system that is installed to a vehicle for producing exterior or interior sound, such as but not limited to
sound actuators, regardless of its mounting position
3.6
modes
distinct driver-selectable condition which does affect powertrain and transmission setup, such that the
emitted sound of the vehicle may vary, including distinct driver-selectable modes which can affect the
sound emitted by sound enhancement systems
3.7
Irregularities
3.7.1
irregularity
maximum distance of a surface from the measurement edge of the straightedge between two contact
points of the straightedge when placed perpendicular to the surface
Note 1 to entry: Measured in accordance with EN 13036-7.
3.7.2
longitudinal irregularity
irregularity (3.7.1) in the direction parallel to the longitudinal axis of the track
3.7.3
transverse irregularity
irregularity (3.7.1) in the direction perpendicular to the longitudinal axis of the track
3.8
mean profile depth
MPD
average value of the height difference between the profile and a horizontal line through the highest
peak (the peak level) over a 100-mm long baseline
3.9
maximum aggregate size
aggregate upper sieve size (D) based on all-in aggregate grading category of GA90
Note 1 to entry: According to EN 13043.
3.10
Vehicle category M
3.10.1
category M1
vehicles used for the carriage of passengers and comprising no more than eight seats in addition to the
driver's seat
3.10.2
category M2
vehicles used for the carriage of passengers and comprising more than eight seats in addition to the
driver's seat and having a kerb mass (3.1.1) plus the maximum allowable payload not exceeding 5 000 kg
3.10.3
category M3
vehicles used for the carriage of passengers and comprising more than eight seats in addition to the
driver's seat and having a kerb mass (3.1.1) plus the maximum allowable payload exceeding 5 000 kg
3.11
Vehicle category N
3.11.1
category N1
vehicles used for the carriage of goods and having a kerb mass (3.1.1) plus the maximum allowable
payload not exceeding 3 500 kg
3.11.2
category N2
vehicles used for the carriage of goods and having a kerb mass (3.1.1) plus the maximum allowable
payload exceeding 3 500 kg but not exceeding 12 000 kg
3.11.3
category N3
vehicles used for the carriage of goods and having a kerb mass (3.1.1) plus the maximum allowable
payload exceeding 12 000 kg
3.11.4
light duty vehicle
LDV
vehicle primarily used to transport passengers and cargo (e.g., cars, vans, SUVs, pickup trucks), with
category M1 and N1 and N2 with m ≤ 4536 kg and P ≥ 150 kW may be deemed as LDV. (i.e., Class 1
n
through Class 2 Vehicles, as designated by the U.S. Department of Transportation)
3.11.5
heavy duty vehicle
HDV
vehicle other than defined in 3.11.4 with a maximum allowable payload of more than 4 536 kg
4 Tables of symbols and abbreviated terms
Table 1 lists the symbols, terms, and abbreviated terms in the order where they are used for the first
time.
Table 1 — Symbols and abbreviated terms used and corresponding clauses
Symbol Unit Subclause Explanation
P kW 3.3 Total power. Sum of net power of all available propulsion sources.
n
m kg 7.5 Test mass of the vehicle
t
m kg 7.5 Kerb mass of the vehicle
kerb
m kg 7.5 Extra loading for vehicles of category N2 and N3
xload
m kg 7.5 Target mass of the vehicle for vehicles of category N2 and N3
target
m kg 7.5 Unladen rear axle load for vehicles of category N2 and N3
ra load unladen
m kg 7.5 Unladen front axle load for vehicles of category N2 and N3
fa load unladen
m kg 7.5 Driver mass
d
L dB(A) 8.4.1 A-weighted equivalent continuous sound pressure level for the
Aeq,TC
different test conditions. Index TC means either ACC, CST, DEC, DEC
AB, CRS STAT, AC MAX and AC LOW
L dB(A) 8.4.2.1 A-weighted equivalent continuous sound pressure level for the
Aeq,ACC
acceleration test
L dB(A) 8.4.2.2.1 A-weighted equivalent continuous sound pressure level for the
Aeq,DEC
deceleration test without any braking applied
L dB(A) 8.4.2.2.2 A-weighted equivalent continuous sound pressure level for the
Aeq,DEC,AB
deceleration test with auxiliary brake device activated
L dB(A) 8.4.2.3 A-weighted equivalent continuous sound pressure level for the
Aeq,CRS
steady speed test
L dB(A) 8.4.3 A-weighted equivalent continuous sound pressure level for the
Aeq,STAT
standstill test
L dB(A) 8.4.3 A-weighted equivalent continuous sound pressure level for the
Aeq,AC,MAX
standstill test with air conditioning on and ventilation at highest
operation level for maximum cooling
L dB(A) 8.4.3 A-weighted equivalent continuous sound pressure level for the
Aeq,AC,LOW
standstill test with air conditioning off and ventilation speed at
lowest operation level
α % 8.5 Weighting factor for the representative sound pressure level at
STAT
standstill condition
α % 8.5 Weighting factor for the representative sound pressure level at
CRS
steady speed condition
α % 8.5 Weighting factor for the representative sound pressure level at
ACC
acceleration condition
α % 8.5 Weighting factor for the representative sound pressure level at
CST
deceleration condition
L dB(A) 8.5 Representative sound pressure level for the vehicle per cycle com-
Aeq,CYCLE
ponent
URBAN 8.5 Cycle component for urban condition
SUBURBAN 8.5 Cycle component for suburban condition
RURAL 8.5 Cycle component for rural condition
MOTORWAY 8.5 Cycle component for motorway condition
L dB(A) 8.5.1 A-weighted equivalent continuous sound pressure level for the
Aeq,CST
deceleration test, weighted combination of deceleration tests with
and without auxiliary brake device applied
L' dB(A) 8.5.1 Representative sound pressure level for the driving cycle without
TEST
time weighting
L dB(A) 8.5.1 Representative sound pressure level for the driving cycle inclusive
TEST
time weighting
t h 8.5.2 Annual average use time of a vehicle per working day
exp
TTabablele 1 1 ((ccoonnttiinnueuedd))
Symbol Unit Subclause Explanation
L dB(A) 8.5.3 Representative interior sound level for a vehicle according to this
Aeq,INTERIOR
standard
5 Test equipment
5.1 Instrumentation for acoustic measurement
5.1.1 General
The apparatus used for measuring the sound pressure level shall be a sound level meter, or single
microphones connected to a data acquisition system or equivalent measurement systems, meeting the
requirements of class 1 instruments. These requirements are described in IEC 61672-1.
The entire measurement system shall be checked and adjusted by means of a sound calibrator that
fulfils the requirements of class 1 sound calibrators in accordance with IEC 60942.
When no general statement or conclusion can be made about conformance of the sound level meter
model to the full specifications of IEC 61672-1, the apparatus used for measuring the sound pressure
level shall be a sound level meter or equivalent measurement system meeting the requirements of Class
1 instruments as described in IEC 61672-3.
The instruments shall be maintained and calibrated in accordance with the instructions of the
instrument manufacturer.
5.1.2 Calibration
At the beginning of every measurement session, the entire acoustic measurement system shall
be checked and adjusted by means of a sound calibrator as described in 5.1.1. At the end of every
measurement session, the entire acoustic measurement system shall be checked by means of a sound
calibrator as described in 5.1.1. Without any further adjustment, the difference between the readings
at the beginning and the end shall be less than or equal to 0,5 dB. If this value is exceeded, the results of
the measurements obtained after the previous satisfactory check shall be discarded.
The checking and adjustment described in 5.1.2 does not invalidate the conformity of IEC 61672-1
described in 5.1.3 for the purpose of this document.
A bi-yearly IEC 61672-3 calibration permits the use of a daily sensitivity check and adjustment.
NOTE The purpose of the check at the beginning of the measurement session is twofold:
a) To insure the measurement system is in good working order, and
b) To adjust the level consistent with the environmental conditions of the day.
The purpose of the check at the end of the measurement session is also twofold:
— To insure the measurement system remains in good working order, and
— To verify the adjusted level remains within expected tolerances for a repeatable and reproduceable
measurement.
5.1.3 Conformity with requirements
Conformity of the sound calibrator with the requirements of IEC 60942 shall be verified once a year.
Conformity of the instrumentation system with the requirements of IEC 61672-1 shall be verified in
accordance with the procedures of IEC 61672-3 at least every 2 years or after each modification of the
system (software, microphone, etc.). All conformity testing shall be conducted by a laboratory which is
authorized to perform calibrations traceable to the appropriate standards.
NOTE The tests of IEC 61672-3 cover only a limited subset of the specifications in IEC 61672-1 for which
the scope is large (temperature range, frequency requirements up to 20 kHz, etc.). It is not feasible to verify the
whole IEC 61672-1 requirements on each item of a computerized data acquisition system. Computerized data
acquisition system available comply with the necessary specifications of IEC 61672-1 and testing specifications
of IEC 61672-3 as required for this document.
5.2 Instrumentation for vehicle speed and rotational engine speed measurements
5.2.1 Vehicle speed
The road speed of the vehicle shall be measured with instruments meeting specification limits of at
least ±0,5 km/h.
NOTE There are various means for measuring the vehicle speed. Most common at time of publication are GPS
based systems and speed signals taken from the data interfaces available on board. When using such information
sources, it is strongly recommended to verify the precision of these sources with regard to signal quality and
data refresh rate.
5.2.2 Rotational engine speed (if applicable)
If applicable and necessary, the rotational speed of the engine shall be measured with an instrument
meeting specification limit of at least ±2 % at the engine speeds required for the measurements being
performed.
NOTE Rotational engine speed signals are commonly taken from the data interfaces available on-board.
When using such information sources, it is strongly recommended verifying the precision of these sources with
regard to signal quality and data refresh rate.
5.3 Meteorological instrumentation
5.3.1 General
The meteorological instrumentation used to monitor the environmental conditions during the test
shall meet the following specifications:
— within ±1,0 °C for a temperature measuring device;
— within ±1,0 m/s for a wind speed measuring device;
— within ±5,0 hPa for a barometric pressure measuring device;
— within ±5,0 % for a relative humidity measuring device.
6 Test facility
6.1 Outdoor test site
The test site shall be such that the sound radiated by the vehicle to the outside contributes to the inside
noise only by reflections from the road surface and not by reflections from buildings, walls, or similar
large objects outside the vehicle. During the period of measurement, the distance of the vehicle from
large objects shall be greater than 20 m.
NOTE Buildings outside the 20 m distance can have a significant influence if their reflection focuses on the
test track.
The test site shall be substantially level. Longitudinal and transverse slope of the operation distance
shall not exceed the value provided by Annex A.
The test track and the surface of the site shall be dry and free from absorbing materials such as powdery
snow or loose debris.
6.1.1 Test track surface properties
The test track surface shall comply with the specifications of Annex A.
NOTE The influence of the road surface on the overall test result can be very significant. Therefore, it is
necessary to provide specifications on the road surface properties. The specifications laid down in Annex A are
taken from ISO 10844 and are simplified to allow a larger variety of road surfaces.
6.2 Meteorological conditions
6.2.1 General
The meteorological instrumentation shall deliver data representative of the test site and shall be
positioned adjacent to the test area.
A value representative of air temperature, wind speed and direction, barometric pressure and relative
humidity during the test shall be noted in the test report.
6.2.2 Air temperature
The measurements shall be made when the ambient air temperature is within the range from -10 °C to
40 °C.
If measurements are carried out at air temperatures below 5 °C special attention shall be paid to the
tyre rubber stiffening and its impact on the tyre/rolling sound. See as well the tyres selection in 7.4.
6.2.3 Wind
The tests shall not be carried out if the wind speed, including gusts, exceeds 5 m/s during the test.
NOTE Wind speed above 5 m/s and gusts can have significant influence to the measurement result,
especially when the wind is lateral to the vehicle.
6.2.4 Humidity
The tests shall not be carried out if it is raining, misty, or snow on the road. Rain may cause additional
noise through the roof. Wet roads may cause increased rolling noise due to spray water.
6.3 Background noise
The background noise shall be measured inside of the vehicle in standstill, powered-off, with all doors,
windows and sunroofs closed.
The background noise shall be measured for duration of 10 s immediately before a series of vehicle
tests. The measurements shall be made with the same microphones and microphone locations used
during the test. The maximum A-weighted sound pressure level time-weighted “fast” shall be reported.
For all measurements of A-weighted sound pressure levels, the lower limit of the dynamic range set by
the background noise and by the inherent noise level of the measuring equipment shall be at least 15 dB
below the lowest reported A-weighted sound pressure level of the vehicle.
7 Vehicle conditions
7.1 General
The vehicle shall be equipped as specified by the vehicle manufacturer. Before the measurements are
started, the vehicle shall be brought to its normal operating conditions, which means that essential
components for the operation of the vehicle are at their nominal temperatures as specified by the
manufacturer. This applies especially, but not limited to:
— the cooling water (if applicable);
— oil temperature (if applicable).
The temperature inside the vehicle shall be established in a way, as it is commonly the case during
operation. Excessive noise from the ventilation system or air conditioning due to extreme hot or cold
temperatures shall be avoided.
NOTE The term “normal” as already used above, indicates the nominal setup of the vehicle as foreseen by
the manufacturer. Such “normal operation conditions” are typically explained in owner’s manuals. The purpose
of this document is, to assess the sound inside the vehicle as foreseen by the manufacturer. The driver can turn
on the radio, adjust the ventilation according to his mood or open windows. Such alternative conditions are not in
the scope of this document.
7.2 Battery state of charge
If so equipped, propulsion batteries shall have a state-of-charge sufficiently high to enable all key
functionalities according to the specifications of the vehicle manufacturer. Propulsion batteries shall
be within their component temperature window to enable all key functionalities. Any other type of
rechargeable energy storage system shall be ready to operate during the test.
7.2.1 Active sound systems
Any active sound devices, either for noise control, or sound enhancement, shall operate as foreseen by
the vehicle manufacturer for normal (default) operating condition and not be interfered with during the
measurements.
For development purposes, these devices can be deactivated or set to other driver selectable modes. In
this case, the setup condition of such devices shall be noted in the test report.
7.3 Multi-mode operation
If the vehicle is equipped with multiple driver selectable operating modes, the mode for normal
operation shall be selected, respectively the default operation condition as stated by the manufacturer
in the owner's manual.
For development purposes, other driver selectable modes may be tested. In this case, the setup condition
shall be noted in the test report.
7.4 Tyre conditions
The tyres and rims shall be appropriate for the vehicle. The tyres shall be inflated to the pressure
recommended by the vehicle manufacturer for normal operation. Tyres shall be suitable for the ambient
conditions when the measurements are carried out.
Tyres with special fitment requirements, such as asymmetric or directional design, shall also be
mounted in accordance with these requirements.
Before testing, tyres shall be conditioned (broken-in). Tyre break-in shall be equivalent to about 100 km
of normal on-road operation. Tyres with special fitment requirements shall be broken-in in accordance
with these requirements. The tyres fitted to the test vehicle shall rotate in the same direction as when
they were broken-in.
Apart from the tread wear caused by the break-in procedure, the tyres shall have preferably full tread
depth. The minimum tread depth shall be at least 80 % of the full tread depth.
In case of outdoor measurements, test tyres shall be warmed-up immediately prior to testing for at
least 10 min in the range of the test speed, with moderate lateral and longitudinal acceleration. The
lateral acceleration shall be selected in a way to avoid excessive tread wear effects.
In case of indoor measurements, test tyres shall be warmed-up prior to testing for at least 10 min in the
range of the test speed, with moderate longitudinal acceleration.
7.5 Loading of the vehicle
The vehicle shall be loaded, according to the Table 2.
Table 2 — Vehicle loading
Vehicle category Vehicle test mass
M The test mass m of the vehicle shall be between 0,90 m ≤ m ≤ 1,20 m
1 t kerb t kerb
N The test mass m of the vehicle shall be between 0,90 m ≤ m ≤ 1,20 m
1 t kerb t kerb
N , N m = 50 kg/kW x P with P given in kW
2 3 target n n
Extra loading, m , to reach the target mass, m , of the ve
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