What is ISO 362-3- Measurement of noise- Indoor testing M and N categories about?
ISO 362-3 is a safety standard on the measurement of noise emitted by accelerating road vehicles.
ISO 362-3 specifies an engineering method for measuring the noise emitted by road vehicles of categories M and N by using a semi-anechoic chamber. The specifications are intended to achieve an acoustical correlation between testing the exterior noise of road vehicles in a semi-anechoic chamber and outdoor testing as described in ISO 362-1.
ISO 362-3 provides all necessary specifications and procedures for indoor testing to obtain results which are comparable to typical run-to-run variations of measurements in today’s type approval tests. ISO 362-3 provides a method designed to meet the requirements of simplicity as far as they are consistent with the reproducibility of results under the operating conditions of the vehicle.
Note 1: The results obtained by this method give an objective measure of the noise emitted under the specified conditions of the test.
Note 2: If measurements are carried out in rooms that do not fulfill the requirements stated in ISO 362-3, the results obtained can deviate from the results using the specified conditions.
Who is ISO 362-3- Measurement of noise- Indoor testing M and N categories for?
ISO 362-3 on indoor testing M and N categories is relevant to:
- Testing authorities
- Manufacturers of noise testing equipment
- Manufacturers of apparatus for measuring sound levels
- Acousticians
Why should you use ISO 362-3- Measurement of noise- Indoor testing M and N categories?
The exterior sound output of a vehicle is one of the standards that manufacturers must consider while designing and developing automobiles. Sound output should be controlled in all driving circumstances for health and environmental reasons. However, there is a rising understanding that automobiles must not be too quiet to be heard by pedestrians and not endanger them.
To achieve these needs, a reliable test facility that can run year-round regardless of weather or other external circumstances is required. In many locations, the weather is so bad that outside testing on a traditional proving field is only practicable for a short period. As a recognized type of approval test track, ISO 362-3 specifies an indoor noise test bench and a test protocol for exact results. Results should be within the run-to-run variation of the valid external noise test given in ISO 362-1, which is used for vehicle type certification. Certain vehicle sound emissions (such the minimal sound emission of electric cars) may be tested on an interior test bench in the future, as natural background noise may prevent testing on an outdoor test track. ISO 362-3 requirements might be incorporated into a future minimum noise test technique. ISO 362-3 offers the essential criteria and methods to assure comparability between current outdoor testing and future interior testing. For equipment, measurement uncertainty, and test methods, ISO 362-3 has them all.
Overall, ISO 362-3 is useful as it specifies an indoor test that gives tight specifications for the equipment and setup, such as the acoustical treatment, the microphone arrays, the roller bench, the adjustment for the dynamic behaviour of the vehicle on the roller test bench, the preconditioning of the vehicle, as well as the thermal conditions for testing.