Document ID: chunk:federal_register_of_legislation:F2006L01279:body:0:p10
Version: federal_register_of_legislation:F2006L01279
Segment Type: other
Provision Reference: 
Character Range: 27669–30481

which results in the microphone being at the greatest possible distance from the vehicle.
    3.2.8   For vehicles fitted with two or more exhaust outlets connected to separate silencers or spaced more than 500 mm apart, each exhaust outlet shall be treated separately as if it was the only one.
    3.2.9   Notwithstanding anything to the contrary in the preceding paragraphs if the microphone positioning procedures result in no suitable position due to an obstruction being part of the vehicle or in an obstruction being directly between the microphone and the exhaust outlet, the requirements of paragraphs 3.2.2 and 3.2.3 may be varied.

3.3   Vehicle operation and noise measurement.
    3.3.1   The vehicle shall be stationary with the transmission in neutral or, in the case of a vehicle with automatic transmission, with the gear selector in the "park" position if such a position is provided.
    3.3.2   In the case of Goods Vehicles and Omnibuses powered by a 'Diesel Engine' the engine shall be operated in accordance with the following procedure.
3.3.2.1 With the engine at idling speed the accelerator pedal of the vehicle shall be
    depressed as rapidly as possible and kept fully depressed until the speed of the engine is substantially stable at maximum (or governed) speed. The accelerator pedal shall then be permitted to return to its original position as rapidly as possible and left in that position until the engine has returned to idling speed.
3.3.2.2 A single noise level measurement shall be made for each microphone position in
use by noting the maximum noise level indicated during this procedure.

    3.3.3   In the case of all other vehicles the engine shall be operated in accordance with the following procedure.
3.3.3.1 The engine shall be brought to 3/4 'ESMP' and stabilised at that speed.
3.3.3.2 A single noise level measurement shall then be made.

    3.3.4   The specified procedure shall be repeated until four consecutive readings having a range less than or equal to 1dB(A) are obtained for each microphone position used.

3.4   Interpretation of results for stationary vehicles.
    3.4.1   Where one microphone position is used the noise level of the vehicle shall be the arithmetic mean of the four readings specified in paragraph 3.3.4.
    3.4.2   When the sound level of the vehicle has been calculated, non-integer results shall be rounded down to the nearest whole decibel.
    3.4.3   Where more than one microphone position is used the noise level at each microphone position shall be determined as if it was the only one. The noise level of the vehicle shall be the higher or highest noise level so calculated.
    3.4.4   If the microphone position is less than 1m from the engine compartment of the vehicle the calculated noise level shall be reduced