In a natural environment, certain ambient noises persist. A chirping bird, a scuttling squirrel, a tree branch bending in the wind—these familiar sounds are constant. When a car cuts through a nearby road, however, the noise of its acceleration dominates the sound space. Carefully measuring these noises, which is covered by SAE J 2805-2020: Measurement Of Noise Emitted By Accelerating Road Vehicles, can be complicated.
Personal human perception, physiological human conditions, culture, and environmental conditions can distort the subjective appraisal of motor vehicle sound. The methods outlined in SAE J 2805-2020 give an objective measure of the noise emitted under specified testing conditions to reproduce the level of noise emitted during normal driving in urban traffic.
About SAE J2805-2020
SAE J 2805-2020 is used to measure the noise emitted by road vehicles. Specifically, the standard specifies, in a performance-based and technology-neutral manner, an engineering method for measuring the 90% percentile exterior noise emitted by road vehicles of categories M and N under typical urban traffic conditions. With this, the document excludes vehicles of category L1, L2, L3, L4, and L5.
The specifications found within this standard are intended to reproduce the level of noise generated by the principal noise sources during normal driving in urban traffic. The test method requires an acoustical environment obtained only in an extensive open space, which is used during measurements of vehicles for regulatory certification and/or type approval, measurements at the manufacturing stage, and measurements at official testing stations.
For the test method, SAE J 2805-2020 outlines a range of specifications for calculating acceleration, the necessary test apparatus, meteorological conditions, background noise, tire selection, operating conditions, calculating engine power, gear selection, target conditions, etc.
Motor Vehicle Categories
SAE J 2805-2020, as specifically noted in its scope, is used for testing road vehicles that fall under the categories M or N. Categories for road vehicles are harmonized by the United Nations Economic Commission for Europe (UNECE). Under this classification:
Category M refers to power-driven vehicles with at least four wheels that carry passengers
Category N refers to power-driven vehicles with at least four vehicles that carry goods
Category L, which is not covered by the scope of this standard, refers to motor vehicles with fewer than four wheels (although Category L6 and L7 refer to certain four-wheeled vehicles). For example, Category L1 and L2 refers to mopeds.
Changes to SAE J 2805-2020
In other words, this standard is based on ISO 362-1:2015 with additional clarifications based its review by the SAE Light Vehicle Exterior Noise Committee and editorial changes to bring the document into alignment with SAE editorial standards. During the 2020 revision, further updates were based on changes to ECE R51.03 adopted through 2019.
With these changes, SAE J 2805-2020 incorporates updates reflecting practical experience and clarifications to improve the understanding of users regarding the intent of the standard.
SAE J 2805-2020: Measurement Of Noise Emitted By Accelerating Road Vehicles is available on the ANSI Webstore.