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The interior floor of a vehicle cabin occupies a significant amount of surface area in proportion to the cabin as a whole, and as such provides a prime opportunity for acoustic treatment. Generally speaking, floor materials must be relatively limp to achieve high acoustic performance. However, the tactile quality of a vehicle floor is very important. The end customer has an expectation for how it should feel to step onto the floor of a vehicle: a carpet should “give” slightly, but not compress fully, under pressure. A carpet that is too stiff or not stiff enough may be perceived as indicative of low quality. Thus, acoustic targets and stiffness targets tend to be at odds. A vehicle interior floor is a trim component which consists of different layers and which can have different pile-up configurations. Such a pile-up typically consists of a soft layer, called a decoupler, and a top layer.

Using a tube apparatus, sound transmission loss measurements can be performed per ASTM E2611-09. Usually the intent of these measurements is to determine the sound transmission of an infinite sheet of material (i.e. the one-dimensional (1D) absorption) of a specific thickness. These results are used in simple room acoustics models and in finite element models. The tube measures the sound transmission loss of a round sample constrained within a tube which, due to edge constraint, can be quite different from the 1D transmission loss. This same issue is seen when measuring the sound absorption of material samples. The edge constraint effect is examined for automotive materials (sheet metal and vinyl barrier material) measured in a tube configured to measure transmission loss, and alternate mounting methods are investigated. The results are compared to theoretical results.

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.