IS 12832: AUTOMOTIVE VEHICLES — INTERIOR NOISE — METHOD OF MEASUREMENT AND REQUIREMENTS

2010·0.9 MB·English

by  Bureau of Indian Standards

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IS 12832 (2010): AUTOMOTIVE VEHICLES — INTERIOR NOISE —
METHOD OF MEASUREMENT AND REQUIREMENTS [TED 4: Automotive
Braking Systems]
“!ान $ एक न’ भारत का +नम-ण”
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IS 12832 : 2010
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Indian Standard
AUTOMOTIVE VEHICLES — INTERIOR NOISE —
METHOD OF MEASUREMENT AND REQUIREMENTS
( First Revision )
ICS 17.140.30; 43.020
© BIS 2010
B U R E A U O F I N D I A N S T A N D A R D S
MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG
NEW DELHI 110002
August 2010 Price Group 3
Automotive Braking Systems, Vehicle Testing and Performance Evaluation Sectional Committee, TED 4
FOREWORD
This Indian Standard (First Revision) was adopted by Bureau of Indian Standards, after the draft finalized by
the Automotive Braking Systems, Vehicle Testing and Performance Evaluation Sectional Committee had been
approved by the Transport Engineering Division Council.
This standard was first published in 1989. This revision has been taken up to include the requirement of
various types of vehicles and test method as specified in AIS 020.
While formulating this standard considerable assistance has been derived from the following:
ISO 5128 : 1980 Acoustics—Measurement of noise inside motor vehicle published by International
Organization for Standardization
JASO Z 111 : 83 Measurement of noise inside motor vehicle issued by Society of Automotive Engineers
of Japan
Publication 179 Precision sound level meters, second edition of the International Electrotechnical
Commission (IEC)
For the purpose of deciding whether a particular requirement of this standard is complied with, the final value,
observed or calculated, expressing the result of a test or analysis, shall be rounded off in accordance with
IS 2 : 1960 ‘Rules for rounding off numerical values (revised)’. The number of significant places retained in
the rounded off value should be the same as that of the specified value in this standard.
IS 12832 : 2010
Indian Standard
AUTOMOTIVE VEHICLES — INTERIOR NOISE —
METHOD OF MEASUREMENT AND REQUIREMENTS
( First Revision )
1 SCOPE At the beginning and end of each series (full set) of
measurements, the sound-level meter must be
This standard specifies the requirements and method calibrated according to the manufacturer’s
of measurement of interior noise of body built N2, instructions by means of an appropriate sound
N3, M2 and M3 category of vehicles specified in source (for example a piston phone). If the sound
IS 14272 (Part 1). level meter errors registered during this calibration
exceed 1 dB (A), the test shall be considered invalid.
2 REFERENCES
4.2 Speed Measurements
The following standards contain provisions, which
The engine speed and vehicle speed shall be
through reference in this text, constitute provisions
determined with an accuracy of ±3 percent during
of this standard. At the time of publication, the
testing.
editions indicated were valid. All standards are
subject to revision and parties to agreements based 5 ACOUSTICAL ENVIRONMENT, WEATHER
on this standard are encouraged to investigate the CONDITIONS, BACKGROUND NOISE
possibility of applying the most recent editions of
5.1 The test site shall be such that the sound
the standards indicated below:
radiated by the vehicle to the outside contributes to
IS No. Title the inside noise only by reflections from the road
surface and not by reflections from buildings, walls
9211:2003 Terms and definitions of weights or similar large objects outside the vehicle. During
of road vehicles other than two the period of measurement, the distance of the vehicle
and three wheeler (second from large objects shall be more than 20 m.
revision)
5.2 Meteorological Conditions
9779:1981 Sound level meters
Measurements shall not be made if wind velocity is
14272 (Part 1) : Automotive vehicles — Types —
more than 3 m/s. It shall be ensured that the results
1995 Terminology: Part 1 Three and
are not affected by gusts of wind.
four wheelers
5.3 Background Noise
3 MEASURED QUANTITIES
Background noise shall be measured by the
3.1 All readings of the sound level meter shall be
microphone located at the driver’s seat of stationary
taken with the dynamic characteristic – ‘fast’.
vehicle, which shall be lower than the measured test
3.2 The values to be measured at all microphone value by 10 dB (A). A suitable windscreen as
positions during the tests are A-weighted sound recommended by sound level meter manufacturer
pressure levels, L , expressed in decibels dB (A). may be fitted to the microphone provided that its
pA
effect on the sensitivity and directional
4 MEASURING INSTRUMENTS
characteristics of the microphone is taken into
4.1 Acoustic Measurements account.
The apparatus used for measuring the noise level 6 TEST TRACK CONDITIONS
must be a precision sound-level meter of the Type O
6.1 Interior sound pressure levels of motor vehicles
using the ‘fast’ response of the sound-level meter
are greatly influenced in general by the macro texture
and the ‘A’ weighted as per IS 9779. The ‘Frontal’
of surface roughness of the road, with smooth road
mode of operation of the sound level meter shall be
surfaces producing consistent interior levels.
used.
Accordingly, the test road shall be hard and as

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IS 12832 : 2010
smooth and levelled as possible, without gaps or auxiliary equipment is automatic in operation, its
ripples or similar macro-texture of surface roughness operating condition shall be stated in the test report.
which might contribute to the interior sound pressure
7.3.3 Adjustable seats shall be set in the mid-
levels of the motor vehicle.
position of the horizontal and vertical range of
The surface shall be dry and free from snow, dirt, adjustments. If the back-rest of the seat is adjustable,
stones, leaves, etc. it shall be set as near to the vertical position as
possible. Adjustable headrests shall be set at the
6.2 The test track shall allow a steady speed to be
mid-position.
maintained. It shall be in a straight line or form a
closed circuit with at least 2 000 m length and having 7.4 Vehicle Operating Conditions
a minimum radius of 200 m. The measurement shall
not be carried out on banking section of tracks. The vehicle operating conditions shall be such as to
typify the inside noise under whichever of the
7 VEHICLE CONDITIONS following conditions are appropriate for the vehicle
under test:
7.1 Engine and Tyre Conditions
a) Steady speeds (see 7.4.1);
Prior to test, the vehicle shall be run-in as per vehicle
manufacturers’ recommendation. The vehicle’s tyres b) Full throttle acceleration (maximum
must be of the type normally fitted to such vehicles accelerator position) (see 7.4.2); and
by the manufacturer and must be inflated to the c) Vehicle stationary, with engine idling and
appropriate pressure(s) for the unladen vehicle. full throttle (see 7.4.3), as an additional
monitoring test for commercial vehicles and
Before the measurements are made, the engine must
buses with diesel engines.
be brought to its normal operating condition as
regards temperatures, settings, fuel, spark plugs, The corresponding operating conditions are
carburetor(s), etc (as appropriate). If the vehicle is specified in 7.4.1, 7.4.2 and 7.4.3.
fitted with fan(s) having an automatic actuating
mechanism, this system must not be interfered with 7.4.1 Steady Speed
during the measurements.
7.4.1.1 Test vehicle speed
7.2 Loading of the Vehicle
The test shall be carried out with increments of
The vehicle shall be tested in unladen condition. 20 km/h starting from 40 km/h to 80 percent of
Only standard vehicle equipment, measuring the maximum speed. If the maximum speed of the
equipment and necessary personnel shall occupy the test vehicle is below 120 km/h, the test speed shall
interior of the vehicle. Not more than two persons be 80 percent of its maximum speed.
(the driver and observer) shall be present, and in M3
For a vehicle with the maximum vehicle speed below
category buses with more than eight seats not more
40 km/h, the test shall be done at 80 percent of its
than three persons may be present.
maximum speed. The vehicle speed shall be
For vehicles with drive-away chassis submitted for maintained within ±3 percent of each test speed.
test, the compliance to 7.4.3 and 10 shall be
7.4.1.2 Gear position of transmission
established based on a prototype model/mock-up
sample, representing completely built vehicle The highest possible gear (including that of auxiliary
submitted by the vehicle manufacturer. transmission) that allows the stable running of the
test vehicle shall be used for each test speed. If the
7.3 Openings, Windows, Auxiliary Equipment,
test vehicle is capable of selecting 4-wheel drive or
Adjustable Seats
2-wheel drive the vehicle shall be run with the
7.3.1 Openings such as skylights, all windows and 2-wheel drive.
ventilating inlets and/or outlets shall be shut if
‘A’ weighted sound pressure levels are to be
possible, unless their influence upon the sound level
determined at least three speeds to cover the range
inside the vehicle is to be investigated.
specified above.
7.3.2 Auxiliary equipment such as windscreen
7.4.2 Full Throttle Acceleration (Maximum
wipers, heating and/or ventilating fans and air-
Accelerator Position)
conditioners shall not operate during the tests. If
the contribution of the noise of the ventilating
The procedure for the acceleration test is as follows:
system, and of any auxiliary equipment, to the total
inside noise is to be investigated, the test should be a) Speed of the vehicle and of the engine shall

repeated with this equipment operating. If any be stabilized at specified initial conditions;
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IS 12832 : 2010
b) When stable conditions are attained, the a) Engine shall be operated at the low speed
throttle shall be fully opened as quickly as idle; and
possible and sound recording shall be made
b) Throttle shall be fully opened as quickly as
until either 90 percent of the engine speed
possible allowing the engine to accelerate
for maximum power as specified by the
to high idle and shall be held fully open for
manufacturer of the vehicle ( in the
at least 5.
following test, referred to as maximum power
speed) or 120 km/h is reached, whichever is 8 MICROPHONE POSITIONS
lower. Wheel slip shall be avoided.
The noise inside a vehicle may vary considerably
The initial operating conditions shall be specified as with location. Therefore, measuring points should
follows: be selected in sufficient number and in such a manner
that the distribution of the noise in the vehicle is
a) Transmission setting shall be the highest
adequately represented with respect to driver and
position making the test possible without
passenger ear locations.
exceeding 120 km/h;
8.1 One measuring point shall be at the driver’s
b) Setting shall not be changed during the test;
position. Additional measuring points shall be for
c) If, at an engine speed of 90 percent of
the rear passenger seats of vehicle adjacent to the
maximum power speed, a road speed of
longitudinal axis of the vehicle.
120 km/h is exceeded in top gear, a lower
gear shall be selected, but no lower than 8.2 For a vehicle with three or more than three rows
third for a four-or five-speed gear-box, and of seats the interior noise shall be measured with the
no lower than second for a three-speed gear- microphone position at the following three positions.
box. If 120 km/h is still exceeded in this lower
Driver’s ear as the first position, second position at
gear, the vehicle shall be tested over the
the middle row of the multiple seat rows and third
speed range 60 to 120 km/h in that gear;
position at the last row of seats for the seat positions
d) If possible, kick-down mechanisms shall be nearest to the longitudinal axis of the vehicle.
made in-operative;
8.3 Both seated and standing positions shall be
e) Initial engine speed shall be the lowest
included where appropriate. The exact position of
allowing a continuously increasing engine
the measuring points shall be indicated on a plan.
speed during the test, but no lower than
45 percent of the maximum power speed, 8.4 During the measurement no person shall occupy
unless 120 km/h is exceeded at 90 percent of the selected position with the exception of the
maximum power speed in the lowest gear driver’s seat. The microphone shall be no closer than
allowed, in which case the initial engine 0.15 m to walls or upholstery. The microphone shall
speed shall be that corresponding to a road be oriented horizontally, with the direction of
speed of 60 km/h; maximum sensitivity specified by the manufacturer
of the microphone pointing in the direction in which
f) For vehicle with automatic transmission, the
a person occupying the seat or standing position
initial engine speed shall be stabilized as
would be looking or, if such direction is not defined,
near as possible to 45 percent of the maximum
power speed. The corresponding road speed in the driving direction.
shall be not higher than approximately
The microphone used during the tests shall be
60 km/h.
mounted in such a way that it is not affected by
If, for vehicles with automatic transmissions, the vibrations of the vehicle. The mounting shall prevent
setting changes before the final speed of 90 percent excessive (more than about 20 mm) amplitudes
of maximum power speed of 120 km/h is reached the relative to the vehicle.
initial speed shall be 50 percent of that speed where
If not stated otherwise by the manufacturer of the
the setting changes.
sound lever meter the direction of maximum
NOTE — Since difficulties in controlling engine speeds sensitivity shall coincide with the reference direction.
may be encountered in vehicles fitted with torque
converters, the test condition should be adhered to as 8.5 Microphone Position with Respect to a Seat
closely as practicable.
The vertical coordinate of the microphone shall be
7.4.3 Stationary Test
0.7 ± 0.05 m above the intersection of the occupied
The procedure for the stationary test which shall be seat surface and the surface of the back of the seat
carried out in neutral gear is as follows: (see Fig 1).
3
IS 12832 : 2010
NOTE — A= Unoccupied seat B= Driver’s seat
FIG. 1 MICROPHONE POSITION WITH RESPECT TO A SEAT
The horizontal co-ordinate shall be the middle plane right (to the left for right-hand driven vehicles) from
(or plane of symmetry) of the unoccupied seat. At the middle plane of the seat. Adjustable seats shall
the driver’s seat, with the driver present, the be set according to 7.3.
horizontal co-ordinate shall be 0.2 ± 0.02 m to the
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IS 12832 : 2010
8.6 Microphone Position for Standing Locations
Sl No. Parameters to be Included in Test Report
The vertical co-ordinate shall be 1.6 ± 0.1m above (1) (2)
the floor. The horizontal co-ordinates shall i) Nature of tests
correspond to a person standing at selected points.
ii) Test site
8.7 Microphone Position in Sleeping-Berths iii) Weather conditions including speed and
direction of wind
In sleeping-berths, such as in sleeper trucks or buses
iv) Measuring equipment
the microphone shall be placed 0.15 ± 0.02 m above
the middle of the unoccupied pillow. v) Background noise and corrections applied
to the date (if any)
9 TEST PROCEDURE
vi) Vehicle details, including,
9.1 At the steady speeds, the values of the A- a) its engine
weighted sound pressure level are recorded for at
b) settings of gearbox
least three speeds as specified in 7.4.1.
c) speed during tests
9.2 At full throttle acceleration (see 7.4.2), the
d) tyre sizes
maximum value of the A-weighted sound pressure
e) tyre pressures
level occurring in the specified acceleration range is
retained and stated in the test report. f) radiator-flaps (blinds)
g) cooling fan
9.3 In the stationary test, the maximum value of the
h) noise shield
A-weighted sound pressure level shall be recorded
when the testing is carried out as specified in 7.4.3. vii) Position of openings with reference to 7.3.1
viii) Auxiliary equipment and its operating
9.4 At least two measurements shall be made at
conditions with reference to 7.3.2
each microphone position and for each operating
condition. If the spread of results of the A-weighted ix) Adjustable seats with reference to 7.3.3
sound pressure levels obtained under any measuring x) Unladen weight of the vehicle
condition exceeds 3 dB (A), further measurements
xi) No. of persons in the vehicle
shall be made until the readings of two independent
xii) Microphone positions (indicated in Plan)
successive measurements fall within a range of
3 dB (A); the mean value of these two readings shall be xiii) A-weighted sound pressure levels at
recorded as the test result. The values stated in the test specified microphone positions
report shall be rounded to the nearest integral decibel.
12 TECHNICAL SPECIFICATIONS OF VEHICLE
Any peak which is obviously out of character with TO BE SUBMITTED BY THE VEHICLE
the general sound pressure level being read should MANUFACTURER
be ignored.
The technical specification of vehicle as relevant to
9.5 Whenever the sound level meter reading interior noise shall be declared by vehicle
fluctuates, the mean value of the readings shall be manufacturer and shall contain at least the following:
determined. Occasional extreme peaks should be
a) Model name/Variant(s)
disregarded.
b) Category of vehicle
10 REQUIREMENTS
c) Unladen weight
10.1 When tested as specified in 7.4.3, the sound d) Fully built or partially built or only with cabin
pressure level shall not exceed 90 dB (A). e) Setting of gear box
10.2 Correction of Results for Different Categories 1) Type of gear box — MT/AT
of Vehicles 2) No. of forward gears
3) Maximum speeds in different gear
In order to take into account the inaccuracies in the
4) Transmission ratio
measuring instruments, the result obtained from each
measurement is determined by deducting 1 dB (A) 5) Axle ratios
from the meter reading f) Design and material used inside the cabin
11 TEST REPORT g) Radiator-flaps (blinds)
h) Cooling fan details
The test report shall include the following
1) Type — Fixed/Viscous/Electrical
information: