This part of the standard applies to motorcycles of categories L3, L4 and L5. Part 1 applies to cars, buses and trucks (categories M and N) and has been adopted as DIN ISO 362-1:2009. When passing measuring microphones, which are located at a height of 1,2 m and at a lateral distance of 7,5 m on a test track in accordance with DIN ISO 10844, defined operating conditions apply for every vehicle category. Both parts replace ISO 362:1998, the new version of which had become necessary, as the previously defined measurement of noise emitted by road vehicles at full acceleration in second or third gear provides results which do not longer correspond to the present conditions in urban traffic. This leads to the fact, that limit reductions, which are based on these measurement results, do not result in an appropriate reduction of traffic noise emissions. Only if the measurement procedure is representative of realistic driving behaviour in urban traffic, the noise levels measured according to the procedure correspond to the actual noise emission of the vehicles used in traffic; only then it can be practically used for the specification of emission limits and consequently make an effective contribution to the reduction of traffic noise in conurbations. The procedure allows for the determination of the actual driving noise levels in urban traffic, typically on roads with speed limits between 50 km/h and 70 km/h. Results have shown that the usual acceleration behaviour under partial load is on the one hand especially disturbing for dwellers, on the other hand it can not be measured with good reproducibility. The results determined according to this procedure give an objective measure of the noise emitted under the specified conditions of test which shall be distinguished from the subjective appraisal of the noise annoyance. Annoyance is strongly related to personal human perception, physiological human conditions, culture and environmental conditions, increases the variation and is therefore not useful as a parameter to describe a specific vehicle condition. In order to simulate the actual driving behaviour under partial load in daily urban traffic, the procedure comprises two operating conditions, this means, one wide-open-throttle acceleration phase, and a constant speed phase. Regarding the noise generation, the combination of these two primary operating conditions was found to be equivalent to the partial throttle and partial power acceleration (engine load). Both primary conditions are also easier to repeat and to compare than the acceleration with partially open throttle. The new procedure specified in this part 2 of the standard is the result of international projects performed to investigate the driving behaviour of motorcycles with regard to exhaust emissions. The collected data were used to develop a test cycle for exhaust emissions (Wordwide Motorcycle Exhaust Emission Test Cycle, WMTC), which has been adopted as UNECE Global Technical Regulation, and at the same time to specify a noise measurement procedure in the International Standard ISO 362-2:2009. The preparation of ISO 362-2 had been preceded by several extensions of the databases and the conduction of a comprehensive test programme, to assure practical considerations and technical accuracy. The necessary test conditions are usually provided for type approval measurements, measurements at the manufacturing stage and measurements at official testing stations. The International Standard has been prepared by ISO/TC 43/SC 1/WG 42 "Joint TC 43/SC 1 - TC 22 WG: Measurement of noise emission (external) from road vehicles". On the national level the responsible Subcommittee is NA 001-01-05-03 UA "Straßenfahrzeuge - Kenngrößen" ("Road vehicles - Parameters") of NALS.