Interior Sound Path Analysis and Noise Reduction Program for a Class 8 Truck

An interior noise study was performed on a Class 8 truck to determine the dominant sound paths into the cab and develop acoustical treatments to improve the sound quality at the driver's location. In-cab sound pressure level and sound intensity measurements were taken at various operating conditions with the truck on a chassis dynamometer inside a hemi-anechoic chamber. Additionally, sound intensity measurements were taken inside a cab buck to obtain detailed information on the sound paths through the front of dash area. Using the data collected, a model was created to identify the sound paths into the cab and understand design requirements for the potential treatment options. Noise control materials were tested and selected to meet the design criteria, and prototype treatments developed to fit properly within the cab interior. Once the treatment package was installed in the truck, its performance was verified with in-cab measurements. The treatment development and evaluation process is presented, along with data showing the noise reduction obtained by the final treatment package.