Weight reduction is a significant concern for automotive manufacturers, and is often achieved by removing as much mass as is safe from the structure of the vehicle. This has a negative effect on the interior acoustics, which has become more and more of an issue as technology has advanced and people expect to be able to do business and consume media in their vehicles. Traditional acoustic treatment tends to be very heavy, which eliminates some of the weight savings.
Recently a vehicle study was performed to determine if the current production sound package in a highly-rated sport utility vehicle could be maintained or improved while reducing the weight. This paper presents the results of that study. The study focused on road noise transmitted through the floor (carpet, rear wheelhouse inner and trunk insulation) and engine noise transmitted through the dash (dash inner). Testing was performed both at the vehicle level on the road and at the component level in the laboratory. It was found that the lightweight sound package was highly effective against road noise, but less effective against engine noise. Additional evaluation was performed to determine if underbody treatment would improve the performance, and it was found the addition of absorption to the underbody of the car helps with road noise, but less so with engine noise.
Ultimately, the lightweight parts, working together as a system, provided sound absorption in the frequency range of interest while still providing the necessary sound transmission loss along the noise paths.