Document ID: chunk:federal_register_of_legislation:F2006L01279:body:0:p5
Version: federal_register_of_legislation:F2006L01279
Segment Type: other
Provision Reference: 
Character Range: 15441–18190

Level Meters", concerning the characteristics of sound level meters, shall be used. Measurement shall be carried out with a weighting network and a time constant conforming to "curve A" and the "fast response" respectively.
    1.2   The sound level meter shall be calibrated against a standard noise source immediately before and after each series of test runs. If the meter reading obtained from either of these calibrations deviates by more than 1dB(A) from the corresponding reading taken at the time of the last free-field calibration the test shall be considered invalid. The actual deviation shall be recorded.
    1.3   The rotational speed of the engine shall be measured by an independent tachometer whose accuracy is within 3 per cent of the actual speed of rotation.

2. Procedure for Vehicles in Motion
(Refer to diagram - Section 4)
2.1   Site for tests on vehicles in motion.
    2.1.1   The measurements shall be made at an open site where the ambient and wind noise levels are at least 10 dB(A) below the noise level being measured. The site may take the form of an open space of 25 m radius having a central part of at least 10 m radius, practically level, consisting of concrete, asphalt or similar material and not covered with powdery snow, tall grass, loose soil, ashes or the like. During the test no one shall be in the measurement area except the observer and the driver. Their presence must have no influence on the meter reading.
    2.1.2   The surface of the test track used to measure the noise of vehicles in motion shall be such as not to cause excessive tyre noise.
    2.1.3   Measurements shall not be made under adverse weather conditions. Any sound peak which appears to be unrelated to the characteristics of the general sound level of the vehicle shall be ignored in taking the readings. If a wind guard is used, its influence on the sensitivity and the directional characteristics of the microphone shall be taken into account.

2.2  Vehicle condition.
    2.2.1   Measurements shall be made on unladen vehicles and, except in the case of non-separable vehicles, without trailer or 'Semi-trailer'.
    2.2.2   The tyres of the vehicle shall be of the correct size and shall be inflated to the correct pressure(s) (etc.) for the vehicle in its unladen condition.
    2.2.3   Before the measurements are begun, the engine shall be brought to its normal operating conditions as regards: temperatures, tuning, fuel, sparking plugs, carburettor(s), etc. as appropriate.
    2.2.4   If the vehicle is fitted with more than two-wheel drive, it shall be tested in the drive which is intended for normal road use.
    2.2.5  If the vehicle is equipped with devices which are not necessary for its propulsion, but which