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Car, Truck and Bus - ITEM 01 - Noise

Base Directive: 70/157

Base Regulation: 51

The directive and regulation both cover M1, M2, M3, N1, N2 and N3 category vehicles.

R51 Annex 10 3.1:  The noise of the vehicle is tested dynamically between two points (AA’ and BB’), 20m apart.  The sound is measured in the centre of this at a point 7.5m perpendicular to the line of travel.  At least 4 measurements will be taken on each side of the vehicle.

Tests vary for different vehicle categories.  (R51 Annex 10,,

For example, M1 and M2 vehicles < 3,500kg:

Acceleration Test – The vehicle will approach AA’ at a constant speed of 50km/h.  At point AA’ the accelerator will be fully depressed.  When the rear of the vehicle has passed point BB’ the accelerator will be released.

Constant Speed Test – A constant speed of 50km/h will be maintained between points AA’ and BB’.  The vehicle will be in the same gear as was used for the acceleration test.

R51 Annex 10 3.2:  Static Noise Tests – The engine speed is increased from idle to a target engine speed (  The engine will then be held at the target speed.  The throttle will then be rapidly released and the engine speed returned to idle. 

Sound Level limits are stated in Directive 70/157 Annex I 2.1 and R51 6.2.2