GB/T 44038-2024 PDF English
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GB/T 44038-2024: Requirements and testing methods of warning sound for vehicle reversing---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GBT44038-2024
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 43.040
CCS T 09
Requirements and testing methods of warning sound for
vehicle reversing
ISSUED ON: MAY 28, 2024
IMPLEMENTED ON: JANUARY 01, 2025
Issued by: State Administration for Market Regulation;
National Standardization Administration.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 4
4 Requirements ... 6
4.1 Warning sound requirements ... 6
4.2 Requirements for warning sound device ... 7
4.3 Requirements for vehicle warning sound ... 9
4.4 Warning sound type ... 10
5 Test method ... 11
5.1 Test equipment ... 11
5.2 Test site ... 12
5.4 Performance test of the warning sound device ... 13
5.5 Sound pressure level test of the warning sound device ... 17
Requirements and testing methods of warning sound for
vehicle reversing
1 Scope
This document specifies the terms and definitions, requirements, test methods for
vehicle reversing warning sounds.
This document is applicable to vehicles of categories N2, N3, M2 (maximum design
gross mass greater than 3500 kg), as well as category M3. Other vehicles shall refer to
it.
2 Normative references
The contents of the following documents constitute the essential terms of this document
through normative references in the text. Among them, for dated references, only the
version corresponding to that date applies to this document; for undated references, the
latest version (including all amendments) applies to this document.
GB/T 3785.1 Electroacoustics - Sound level meters - Part 1: Specifications
GB/T 15173 Electroacoustics - Sound calibrators
GB/T 22157 Acoustics - Specification of test tracks for measuring noise emitted by
road vehicles and their tyres
GB/T 28046.4-2011 Road vehicles - Environmental conditions and testing for
electrical and electronic equipment - Part 4: Climatic loads
GB/T 30038 Road vehicles - Degrees of electrical equipment protection (IP-Code)
GB/T 34828 Acoustics - Test methods for the qualification of free-field
environments
3 Terms and definitions
The following terms and definitions apply to this document.
3.1
Warning sound for vehicle reversing
4.1.1.1 Warning sound shall be intermittent and contain at least one silent component
in each cycle.
4.1.1.2 Warning sound shall be one of the following: buzzer tone, broadband tone, 1/3
octave tone or voice combination tone.
4.1.2 Warning sound type requirements
4.1.2.1 Buzzer tone
The buzzer tone emitted by the vehicle when reversing is played in a loop, including a
sound with a main frequency, whose frequency range is 1000 Hz ~ 2800 Hz; the
playback frequency is 90 times/min ± 30 times/min.
4.1.2.2 Broadband tone
The broadband tone emitted by the vehicle when reversing is played in a loop, including
sounds with multiple frequencies, whose frequencies are at least continuous within
1000 Hz ~ 4000 Hz; the playback frequency is 90 times/min ± 30 times/min.
4.1.2.3 1/3 octave tone
The 1/3 octave sound played in a loop when the vehicle is reversing has its main energy
in one of the seven 1/3 octaves; the power spectrum density remains constant in the 1/3
octave. The center frequencies of the seven 1/3 octaves are 800 Hz, 1000 Hz, 1250 Hz,
1600 Hz, 2000 Hz, 2500 Hz, 3125 Hz, respectively. The playback frequency is 90
times/min ± 30 times/min.
4.1.2.4 Voice combination tone
The voice combination tone consists of voice and one of the buzzer tone, broadband
tone, or 1/3 octave tone. The voice is played after the buzzer tone, broadband tone, or
1/3 octave tone. The voice is "Reverse, please pay attention" and shall be in clear and
recognizable Mandarin. The playback frequency is 30 times/min ± 10 times/min.
4.2 Requirements for warning sound device
4.2.1 General requirements
4.2.1.1 The non-self-adjusting sound device shall contain at least the normal level.
4.2.1.2 The multiple warning device system shall cover at least two sound pressure level
modes, one of which is the normal level.
4.2.1.3 The sound emitted by the warning sound device shall reach the minimum sound
pressure level within two cycles.
5 Test method
5.1 Test equipment
5.1.1 Meteorological measuring instruments
Meteorological measuring instruments are mainly used to monitor environmental
conditions during the test; their accuracy shall meet the following requirements:
- Temperature measuring instruments: ±1 °C;
- Wind speed measuring instruments: ±1 m/s;
- Air pressure measuring instruments: ±5 hPa;
- Relative humidity measuring instruments: ±5%.
5.1.2 Acoustic measuring instruments
5.1.2.1 Requirements for acoustic measuring instruments
The sound level meter or other equivalent measuring instruments, which are used for
measurement, shall meet the requirements of Class 1 sound level meters specified in
GB/T 3785.1. The "A" frequency weighting characteristics and "F" time weighting
characteristics described in GB/T 3785.1 shall be used for measurement. When using
an instrument that can periodically monitor the A-weighted sound pressure level, the
time interval between its readings shall not be greater than 30 ms.
For voice combination warning sounds, the measuring instrument shall be able to
measure the sound pressure level of the buzzer warning sound, broadband warning
sound, 1/3 octave warning sound, voice warning sound, respectively, that is, the sound
pressure waveforms of the measured buzzer warning sound, broadband warning sound,
1/3 octave warning sound, voice warning sound are easy to identify and process.
When measuring frequency, the digital sound recording instrument shall be quantized
to at least 16 bits; its average auto-power spectrum shall be determined using a Hanning
window and at least 66.6% overlap average, meanwhile cover the relevant frequency
band.
5.1.2.2 Calibration of acoustic measuring instruments
Before and after measurement, the sound level meter shall be calibrated according to
the manufacturer's requirements using a Class 1 sound calibrator that complies with the
provisions of GB/T 15173. Without any adjustment, if the difference between the latter
calibration reading and the previous calibration reading exceeds 0.5 dB(A), the results
of the relevant tests after the previous calibration are invalid.
The above calibration work for sound calibrators, sound level meters or other equivalent
measuring instruments shall be carried out, by qualified testing institutions in
accordance with the relevant standards.
5.2 Test site
5.2.1 Outdoor conditions
5.2.1.1 Outdoor meteorological conditions
During the test, the meteorological conditions shall meet the following requirements:
- Temperature: -10 °C ~ 50 °C;
- Wind speed: less than or equal to 5 m/s. When the wind speed exceeds 2 m/s, it is
recommended that the microphone use a windshield;
- Meteorological equipment shall provide representative data of the test site and shall
be placed in an area close to the test area, at a height that is the typical microphone
height;
- During the test, there shall be no precipitation in the air (such as rain, hail, etc.);
meanwhile the surface of the test site shall be kept dry;
- During the test interval, the values of temperature, wind speed, wind direction,
relative humidity, air pressure shall be recorded.
5.2.1.2 Outdoor site conditions
The site meets one of the following requirements.
a) Test site that meets the requirements of GB/T 22157.
b) The site shall be an open space with a radius of not less than 50 m. The space shall
not have large reflective objects such as walls, rocks, bridges or buildings. The
central part used for measurement shall be level, within a radius of not less than
20 m. The site shall be a flat open ground made of concrete, dense asphalt or
similar hard materials without obvious pores. It shall not be snow, haystacks,
loose soil or other ground with sound absorption characteristics.
5.2.2 Indoor semi-anechoic or anechoic chamber conditions
Anechoic chambers or semi-anechoic chambers shall meet the requirements of GB/T
34828.
5.3 Test method of background noise sound pressure level
When measuring background noise, the measurement shall be continued for at least 10
s. When calculating background noise using a 10 s sound obtained from the
measurement, it shall be ensured that the sound is typical background noise and does
not contain any transient interference. The measurement shall use the same sound level
meter and sound level meter position as in the test process.
When testing in an indoor semi-anechoic or anechoic chamber, the noise emitted by
other test equipment, including air handling noise, shall be recorded as background
noise.
The highest sound pressure level of the 10 s sound, which is measured from the sound
level meter, shall be recorded as the background noise of the sound level meter; the
range from the maximum to the minimum value of the 10 s sound shall be recorded.
5.4 Performance test of the warning sound device
5.4.1 Test site
The test of the warning sound device should be carried out in an anechoic room. When
it is carried out in a semi-anechoic room or an outdoor site specified in 5.2.1.2, some
precautions (such as sound absorption screens) shall be taken, to avoid the influence of
ground reflection in the measurement area on the measurement results. The background
noise sound pressure level shall be at least 10 dB(A) lower than the sound pressure level
to be measured.
5.4.2 Test voltage
When the nominal voltage of the warning sound device is 12 V, the test voltage is 14 V
± 0.2 V; when the nominal voltage is 24 V, the test voltage is 28 V ± 0.2 V.
5.4.3 Microphone position
The warning sound device shall be firmly installed on the metal base frame according
to the specified installation method. The mass of the base frame shall be at least 10
times that of the warning sound device. It is necessary to ensure that the side reflection
and self-vibration of the base frame will not have a significant impact on the test results
during the test.
The warning sound device shall be kept at the same height as the microphone, which is
1.20 m ± 0.05 m. The center line of the maximum sensitivity of the microphone shall
coincide with the direction of the maximum sound pressure level of the warning sound
device; the offset of the microphone from the center line shall be within the range of
±0.02 m.
When measuring the warning sound, play the reference sound. Each measurement time
is not less than 5 s. The maximum value during the measurement process is taken as the
measurement result. The value shall be rounded off according to the principle of
rounding.
For the stepwise self-adjusting warning device, the total sound pressure level measured
under each reference sound pressure shall meet the requirements of 4.2.2.2. For the self-
adjusting warning device, the total sound pressure level measured under each reference
sound pressure shall meet the requirements of 4.2.2.3.
5.4.4.3 Test of voice combination warning sound pressure level
Measure the voice combination warning sound according to the method specified in
5.4.4.1 ~ 5.4.4.2. Measure the sound pressure level of the buzzer warning sound,
broadband warning sound, 1/3 octave warning sound, voice warning sound,
respectively. The value shall be rounded up according to the principle of rounding up.
Compare the two; the result shall comply with the provisions of 4.2.2.4.
5.4.5 Frequency test
Test under the conditions specified in 5.4.1 ~ 5.4.2. Measure 10 cycles continuously.
Record the frequency value or frequency range in each cycle. The value shall be
rounded up according to the principle of rounding up. For non-self-adjusting warning
sound devices or multiple warning device systems, the difference between the measured
frequency or frequency range and the rated frequency or frequency range shall not
exceed 10%. For stepwise self-adjusting warning devices or self-adjusting warning
devices, the speaker used to play the reference sound shall be turned off during
measurement; the difference between each cycle shall not exceed 10%.
5.4.6 Frequency test
Test the frequency of the warning sound under the conditions specified in 5.4.1 ~ 5.4.2.
The total measurement time shall not be less than 3 minutes. If the last cycle is an
incomplete cycle, it shall also be counted as 1 cycle. The result shall comply with the
provisions of 4.1.2.
5.4.7 Low temperature resistance test
Place the device in a test chamber at -40 °C and test according to the provisions of
5.1.1.1 of GB/T 28046.4-2011.
5.4.8 High temperature resistance test
Place the device in a test chamber at 85 °C and test according to the provision 5.1.2.1
of GB/T 28046.4-2011.
5.4.9 Reliability test
5.4.9.1 Reliability test requirements
If the test is conducted in an anechoic chamber, the anechoic chamber shall be large
enough to ensure the normal dissipation of heat from the warning sound device during
the test.
5.4.9.2 Temperature change resistance test
Place the device in a test chamber at 70 °C for 1 hour; in a test chamber at -30 °C for 1
hour; in a test chamber at 50 °C for 1 hour; in a test chamber at -20 °C for 1 hour.
5.4.9.3 Durability test
Place the device in an environment at 25 °C ± 11 °C and run continuously for 50 hours.
5.4.9.4 Vibration resistance test
Place the device in an environment at 25 °C ± 11 °C, with a vibration cycle of 2000
times/min ± 200 times/min and an amplitude of 2 mm ± 0.2 mm, for 30 minutes in each
of the three directions of x, y, z.
5.5 Sound pressure level test of the warning sound device
5.5.1 Test site
The vehicle test of the warning sound device can be carried out in an anechoic room or
a semi-anechoic room, or in an outdoor site specified in 5.2.1.2.
5.5.2 Vehicle status
The vehicle shall be parked stably at the designated position; the windows shall be
closed; the wheels shall be in a straight-line driving position; the battery voltage shall
be normal; the air conditioning device shall be turned off.
If the vehicle's fan has an automatic start function, it shall be ensured that the fan does
not start during the sound pressure level test.
Other sound-generating devices that affect the measurement results shall be turned off.
5.5.3 Test voltage
The test voltage can be any of the following:
a) Powered by the vehicle battery only;
b) Powered by the vehicle battery when the engine is preheated and the vehicle is
idling;
corrected according to the requirements of 5.5.7. The corrected value shall be rounded
off as the final result according to the principle of rounding off, which shall meet the
requirements of 4.3.2.1.
5.5.6.2 Test of stepwise self-adjusting warning device and self-adjusting warning
device
Test under the conditions specified in 5.5.1 ~ 5.5.5. After the reversing signal is
triggered and the warning sound device starts working, find the maximum sound
pressure level height in the range of 0.5 m ± 0.05 m to 1.5 m ± 0.05 m above the ground.
Fix the microphone at the position of the maximum sound pressure level, to measure
the sound pressure level. The measurement time shall not be less than 10 s. The
maximum value during the test shall be taken as the measurement result. The recorded
data shall be accurate to one decimal place.
Turn off the warning sound device and measure the sound pressure level of the
background noise at this position. The measurement time shall not be less than 10 s.
The maximum value during the measurement shall be taken as the measurement result
at this position. The recorded data shall be accurate to one decimal place.
For the stepwise self-adjusting warning device, the maximum value shall be corrected
according to the requirements of 5.5.7. The difference between the turning on and off
of the warning sound device shall be calculated. The final result shall be rounded off
according to the principle of rounding off, which shall meet the requirements of 4.3.2.2.
For the self-adjusting warning device, calculate the difference between the on and off
of the warning sound device; round it off as the final result according to the principle
of rounding, which shall meet the requirements of 4.3.2.3.
5.5.7 Correction method of sound pressure level
The measured sound pressure level shall be corrected according to Table 6, based on
the difference between the maximum and minimum background noise during
measurement. For the whole vehicle test of the self-adjusting warning device, if a peak
value that is obviously different from the normal sound pressure level is observed
during the test, this data shall be discarded.
Where:
Ltest corr - Test correction value, in decibels [dB(A)];
Ltest - Test value of warning sound pressure level, in decibels [dB(A)];
Lcorr - Correction value, in decibels [dB(A)].
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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