AS ISO 9533:2020 pdf free.Earth-moving machinery一Machine- mounted audible travel alarms and forward horns一Test methods and performance criteria.
4 Apparatus
4.1 Sound level meter with an extension cable or equivalent sound measurement system that meets the performance requirements of IEC 61672-1, Type 1.
It is recommended that for the purposes of this International Standard all sound pressure level measurements be rounded to the nearest whole number in decibels.
4.2 Acoustical calibrator, or equivalent measurement system, recommended to be used each day of measurement to calibrate the sound level meter prior to testing and for checking sensitivity drift after test completion. The effects of atmospheric pressure, temperature and use of a windscreen should be accounted for within the system calibration as recommended by the manufacturer of the instrumentation.
4.3 Microphone wind screen, designed for sound measurement and recommended by the manufacturer of the sound level meter or equivalent sound measuring system, which shall be used to maintain consistency from test to test and add protection to the microphone assembly.
4.4 Anemometer, or other device, for measuring ambient wind speed and direction, accurate to within ±10 % at the highest recommended wind speed.
4.5 Engine rotational frequency indicator with an accuracy to within ±2 % of the indicated engine rotational frequency.
4.6 Thermometer for measurement of ambient temperature accurate to within ±2 °C. NOTE Apparatus will also be needed for checking the test environment (see 5.1).
5 Test environment
5.1 Test area
The test area shall consist of a free field above a hard reflecting plane no rougher than non-porous asphalt. The test area bordered by the machine and the microphone shall also consist of a flat, horizontal surface or surface sloping downwards away from the centre of the test area. No reflective objects such as buildings should be within 30 m of the microphone or the machine being measured.
The test technician or test equipment shall be > 2 m from the sound-measuring microphone during exterior location measurements.
NOTE For further details giving the recommended test area configuration, see ISO 3744 and ISO 6393.
5.2 Background noise
The ambient A-weighted sound pressure level due to sources other than the earthmoving machinery under test, including wind effects, shall be at least 10 dB lower than the lowest measurement of interest.
5.3 Climatic conditions
Measurements shall not be carried out when precipitation, e.g. rain, snow or sleet, is falling or when the ground is snow-covered. The ambient temperature shall be within a temperature range —10°C to +35°C.
NOTE For further details giving recommended climatic conditions, see ISO 6393.
5.4 Wind
The average wind speed at the test site shall be less than 8 rn/s.
Wind speeds at each measurement location due to machine operation should also be below 8 rn/s. For measurement locations where wind speeds are above this value, sound measuring equipment designed for high wind applications should be used.AS ISO 9533 pdf download.