This International Standard specifies a test procedure, environment and instrumentation for measuring the exterior sound pressure levels from road vehicles under stationary conditions, providing a continuous measure of the sound pressure level over a range of engine speeds. This International Standard applies only to road vehicles of categories L, M and N equipped with internal combustion engines. The method is designed to meet the requirements of simplicity as far as they are consistent with reproducibility of results under the operating conditions of the vehicle. It is within the scope of this International Standard to measure the stationary A-weighted sound pressure level during — type approval measurements of vehicle; — measurements at the manufacturing stage; — measurements at official testing stations; — measurements at roadside testing. This International Standard specifies neither a method to check the exhaust sound pressure level when the engine is operated at realistic loads nor a method to check the exhaust sound pressure levels against a general noise limit for categories of road vehicles. Technical background information is given in Annex A.