This document specifies an engineering method for measuring the noise emitted by accelerating highway vehicles of all types (except motorcycles) in intermediate gears with full utilization of the available engine power.
The method is designed to meet the requirements of simplicity and reproducibility of results under realistic vehicle operating conditions.
Measurements relate to operating conditions of the vehicle which give the highest noise level consistent with urban driving and which lead to reproducible noise emissions. Therefore, an acceleration test at full throttle from a stated engine or vehicle speed is specified.
The test method calls for an acoustical environment which can only be obtained in an extensive open space. Such conditions can usually be provided for: a. measurements at the manufacturing stage and b. measurements at official testing stations.
Measurements must be carried out in an acoustical environment which fulfill the requirements stated in this document. It should be noted that spot checking of vehicles chosen at random can rarely be made in an ideal acoustical environment. If measurements have to be carried out on the road in an acoustical environment which does not fulfill the requirements stated in this document, it should be recognized that the results obtained may deviate appreciably from the results obtained using the specified conditions.
The results obtained by this method give an objective measure of the noise emitted under the prescribed conditions of test. However, it is necessary to consider the fact that the subjective appraisal of the annoyance of different classes of motor vehicles is not simply related to the indications of a sound level meter. The motorcycles are covered in other SAE documents that prescribe an operating mode that is more representative of actual use.