ISO 362:1998
(Main)Acoustics — Measurement of noise emitted by accelerating road vehicles — Engineering method
Acoustics — Measurement of noise emitted by accelerating road vehicles — Engineering method
Acoustique — Mesurage du bruit émis par les véhicules routiers en accélération — Méthode d'expertise
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 362
Third edition
1998-06-15
Acoustics — Measurement of noise emitted
by accelerating road vehicles —
Engineering method
Acoustique — Mesurage du bruit émis par les véhicules routiers en
accélération — Méthode d'expertise
A
Reference number
ISO 362:1998(E)
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ISO 362:1998(E)
Contents Page
1 Scope. 1
2 Normative references . 1
3 Definitions. 2
4 Vehicle categories. 2
5 General considerations . 3
5.1 Driving conditions . 3
5.2 Interpretation of results. 3
6 Instrumentation. 3
6.1 Instruments for acoustical measurement . 3
6.2 Instrumentation for speed measurements . 4
6.3 Meteorological instrumentation . 4
7 Acoustical environment, meteorological conditions and
background noise . 4
7.1 Test site . 4
7.2 Meteorological conditions . 4
7.3 Background noise. 5
8 Procedure. 5
8.1 Microphone positions. 5
8.2 Number of measurements. 5
8.3 Conditions of the vehicle . 5
8.4 Operating conditions. 6
8.5 Readings to be taken and reported values . 9
8.6 Measurement uncertainty . 9
9 Test report . 10
Annex A: Measurement uncertainty. 11
Annex B: Bibliography. 12
© ISO 1998
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
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Printed in Switzerland
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ISO ISO 362:1998(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide
federation of national standards bodies (ISO member bodies). The work of
preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which
a technical committee has been established has the right to be represented
on that committee. International organizations, governmental and non-
governmental, in liaison with ISO, also take part in the work. ISO
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard ISO 362 was prepared by Technical Committee
ISO/TC 43, Acoustics, Subcommittee SC 1, Noise.
This third edition cancels and replaces the second edition (ISO 362:1994),
which has been technically revised. The method has been modified in
relation to earlier editions in order to improve the reproducibility.
Annexes A and B of this International Standard are for information only.
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INTERNATIONAL STANDARD ISO ISO 362:1998(E)
Acoustics — Measurement of noise emitted by accelerating road
vehicles — Engineering method
1 Scope
This International Standard specifies an engineering method for measuring the noise emitted by accelerating road
vehicles.
The method is designed to meet the requirements of simplicity as far as they are consistent with reproducibility of
results under the operating conditions of the vehicle.
The specifications are intended to reproduce the noise levels which are produced during the use of intermediate
gears with full utilization of the engine power available as may occur in urban traffic.
The test method requires an acoustical environment which can only be obtained in an extensive open space. Such
conditions can usually be provided for:
type approval measurements of vehicle;
measurements at the manufacturing stage; and
measurements at official testing stations.
NOTE It should be noted that spot checking of vehicles chosen at random can rarely be made in an ideal acoustical
environment. If measurements have to be carried out on the road in an acoustical environment which does not fulfil the
requirements stated in this International Standard, it should be recognized that the results obtained may deviate appreciably
from the results obtained using the specified conditions.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the edition indicated was valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent edition of the standard indicated below. Members of IEC and ISO maintain
registers of currently valid International Standards.
ISO 10844:1994, Acoustics — Test surface for road vehicle noise measurements
IEC 60651:1979, Sound level meters
IEC 60942:1988, Sound calibrators
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ISO 362:1998(E)
3 Definitions
For the purposes of this International Standard, the following definitions apply:
3.1
automatic downshift
gear change to a lower gear (higher transmission ratio) which can be initiated at the will of the driver
NOTE An automatic downshift may be initiated, for example, by a change of pressure on or position of the accelerator
control, thereby activating a special programme which effects downshifts to gears which are lower than those normally used in
urban driving.
3.2
intermediate result
value calculated from the test series measurements and used to determine the reported value
3.3
kerb mass
complete shipping mass of a vehicle fitted with all equipment necessary for normal operation plus the mass of the
following elements:
lubricants, coolant (if needed), washer fluid,
fuel (tank filled to at least 90 % of the capacity specified by the manufacturer),
other equipment if included as basic parts for the vehicle, such as spare wheel(s), wheel chocks, fire
extinguisher(s), spare parts, and tool-kit
NOTE The definition of kerb mass may vary from country to country, but in this International Standard it refers to the
definition contained in ISO 1176.
3.4
rated engine speed, S
engine speed at which the engine develops its rated maximum net power as stated by the manufacturer
4 Vehicle categories
4.1 Category L: motor vehicles with less than four wheels:
L1 and L2: mopeds (see ISO 9645 for further details),
3
L3: two-wheeled motor vehicles with an engine cylinder capacity > 50 cm or maximum speed > 50 km/h,
3
L4: three-wheeled motor vehicles with an engine cylinder capacity > 50 cm or maximum speed > 50 km/h, the
wheels being attached asymmetrically along the longitudinal vehicle axis,
3
L5: three-wheeled motor vehicles with an engine cylinder capacity > 50 cm or maximum speed > 50 km/h,
having a gross vehicle mass rating < 1000 kg and wheels attached asymmetrically along the longitudinal
vehicle axis.
4.2 Category M: motor vehicles with at least four wheels, used for the carriage of passengers:
M1: vehicles used for the carriage of passengers and comprising no more than eight seats in addition to the
driver’s seat,
M2: vehicles used for the carriage of passengers and comprising more than eight seats in addition to the
driver’s seat, and having a maximum mass not exceeding 5 t,
M3: vehicles used for the carriage of passengers and comprising more than eight seats in addition to the
driver’s seat, and having a maximum mass exceeding 5 t.
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4.3 Category N: motor vehicles with at least four wheels used for the carriage of goods:
N1: vehicles used for the carriage of goods and having a maximum authorized total mass not exceeding
3,5 tonnes,
N2: vehicles used for the carriage of goods and having a maximum authorized total mass exceeding
3,5 tonnes but not exceeding 12 tonnes,
N3: vehicles used for the carriage of goods and having a maximum authorized total mass exceeding
12 tonnes.
5 General considerations
5.1 Driving conditions
This International Standard is based on a test with vehicles in motion. Measurements shall be related to operating
conditions of the vehicle which give the highest noise level which may occur during urban driving and which lead to
reproducible noise emission. Therefore, an acceleration test from a stated vehicle speed is specified.
5.2 Interpretation of results
The results obtained by this method give an objective measure of the noise emitted under the specified conditions
of test.
NOTE It is necessary to consider the fact that the subjective appraisal of the annoyance of different classes of motor
vehicles is not simply related to the indications of a sound measurement system.
6 Instrumentation
6.1 Instruments for acoustical measurement
6.1.1 General
The sound level meter or the equivalent measuring system, including the windscreen recommended by the
manufacturer shall at least meet the requirements of Type 1 instruments in accordance with IEC 60651.
The measurements shall be made using the frequency weighting A, and the time weighting F.
When using a system that includes a periodic monitoring of the A-weighted sound pressure level, a reading should
be made at a time interval not greater than 30 ms.
6.1.2 Calibration
At the beginning and at the end of every measurement session, the entire measurement system shall be checked
by means of a sound calibrator that fulfils the requirements for sound calibrators of at least precision Class 1
according to IEC 60942. Without any further adjustment the difference between the readings of two consecutive
checks 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.
6.1.3 Compliance with requirements
The compliance of the sound calibration device with the requirements of IEC 60942 shall be verified once a year
and the compliance of the instrumentation system with the requirements of IEC 60651 shall be verified at least
every 2 years, by a laboratory which is authorized to perform calibrations traceable to the appropriate standards.
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6.2 Instrumentation for speed measurements
The rotational speed of the engine and the road speed of the vehicle during the constant speed approach shall be
measured with instruments meeting specification limits of ±2 % or less.
6.3 Meteorological instrumentation
The meteorological instrumentation used to monitor the environmental conditions shall include the following:
a temperature-measuring device meeting specification limits of 1 C or less;
± °
a wind speed measuring device meeting specification limits of ±1,0 m/s.
7 Acoustical environment, meteorological conditions and background noise
7.1 Test site
The test site should be constructed according to the requirements given in ISO 10844.
The test site shall be substantially level. The surface of the test track shall be dry and its texture such that it does
not cause excessive tyre noise. The test track surface shall meet the requirements of ISO 10844.
The test site shall be such that when a small omnidirectional noise source is placed in its surface at the central point
(intersection of the microphone line and the centre of the vehicle lane), see figure 1, deviations from hemispherical
divergence shall not exceed ±1 dB.
This condition is deemed to be satisfied if the following requirements are met:
a) within a radius of 50 m around the centre of the track, the space shall be free of large reflecting objects, such
as fences, rocks, bridges or buildings;
b) the test track and the surface of the site shall be dry and free from absorbing materials, such as powdery snow
or loose debris;
c) in the vicinity of the microphone, there shall be no obstacle that could influence the acoustical field and no
person shall remain between the microphone and the noise source. The meter observer shall be positioned so
as not to influence the meter reading.
NOTE It is recommended that the test area be a substantially flat plane, particularly in the portion of the area between the
vehicle path and the microphone location (see figure 1).
7.2 Meteorological conditions
The meteorological instrumentation should be positioned adjacent to the test area at a height representative of the
site, except as noted below.
It is recommended that the measurements be made when the ambient air temperature is within the range from 0 °C
to 40 °C.
It is recommended that tests should not be carried out if the wind speed, including gusts, at microphone height
exceeds 5 m/s during the sound measurement interval.
It is recommended that a value representative of temperature, wind speed and direction, relative humidity, and
barometric pressure be recorded during the sound measurement interval.
NOTE When comparing data under different environmental conditions, the effects of temperature and other factors should
be considered.
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Dimensions in metres
NOTE Shaded area (“test area”) is the minimum area to be covered with a surface complying with ISO 10844.
Figure 1 — Test site dimensions
7.3 Background noise
It is recommended that the A-weighted background noise (including any wind noise) be 15 dB below the emissions
produced by the vehicle under test, but it shall always be at least 10 dB below.
8 Procedure
8.1 Microphone positions
The distance from the microphone positions to the centreline of travel CC (see figure 1) on the test track shall be
7,5 m ± 0,05 m.
The microphone shall be located 1,2 m ± 0,02 m above the ground level. The reference axis for free-field conditions
(see IEC 60651) shall be horizontal and directed perpendicularly towards the path of the centreline of travel CC.
8.2 Number of measurements
Make at least four measurements on each side of the vehicle.
8.3 Conditions of the vehicle
The vehicle shall be supplied with fuel, spark plugs, a fuel supply system, etc., as specified by the vehicle
manufacturer.
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Measurements shall be made on vehicles at kerb mass plus the driver and measuring equipment. Except for the
case of non-separable vehicles, measurement shall be made without a trailer or semi-trailer.
The tyres used for the test are selected by the vehicle manufacturer. They shall correspond to one of the tyre sizes
designated for the vehicle by the vehicle manufacturer. In the case of M1 through N3 vehicles, tyres shall not be
used with a tread depth less than 1,6 mm. The tyres shall be inflated to the pressure recommended by the
manufacturer for the test mass of the vehicle.
Before the measurements are started, the vehicle shall be brought to its normal operating conditions with respect to
temperatures and tuning.
8.4 Operating conditions
8.4.1 General conditions
The vehicle shall approach the line AA with the path of its centreline following as closely as possible the line CC
(see figure 1) at the speed and in the gear specified in 8.4.2 to 8.4.5, as appropriate.
When the front of the vehicle reaches the line AA, the accelerator control shall be fully engaged as rapidly as
practicable (without operating the automatic downshift to a lower range than normally used in urban driving) and
held fully engaged until the rear of the vehicle reaches line BB. The accelerator control shall then be released. The
engagement of the accelerator control shall occur as close as possible to the line AA.
Any trailer which is not readily separable from the towing vehicle shall be ignored when considering the crossing of
the line BB.
If the vehicle is fitted with more than two-wheel drive, test it in the drive which is intended for normal road use.
If the vehic
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