Case Study of Pass-By Noise Development on a Class 8 Truck

Governmental regulations regarding exterior noise emitted by motor vehicles vary throughout the world. A vehicle which is compliant in one market may not be compliant in another market. In this case, a production North American class 8 truck was being prepared for sale overseas. The requirement to meet European Union (EU) pass-by regulations as tested per the EU standard meant development of a production feasible package to substantially reduce noise emissions without changing any fundamental design or operating parameters of the truck. The development testing was done on a chassis dynamometer in a hemi-anechoic chamber without any specific pass-by noise simulation software. Efforts to develop a reasonably accurate correlation from lab to track, use of acoustic beamforming for source localization and package design iterations leading to a final successful package are discussed.