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An in-vehicle study was conducted to understand how damping treatments on the floor of a vehicle affect the interior sound in the vehicle. Three differently formulated damping treatments were tested on three similar sport utility vehicles for this purpose. Numerous on-road sound and vibration data were collected under different operating conditions, and were reduced to understand the value of the damping treatment in controlling interior noise caused by powertrain and rolling-tire/road interaction. The paper discusses different data analysis procedures that were used in this study to understand whether there is a damping treatment that performs better than others in spite of variances in test vehicles, and still minimize the adverse influence of other variables that are related to the vehicle performance variation itself.

This paper discusses an analytical tool that has been developed to predict what types of interior sound package treatments may be necessary in a truck cab to meet a predetermined target sound level at the driver location. The steps that were taken to develop this tool involved a combination of experimental measurement and analytical based studies. Measurements were conducted to identify the acoustic strengths of the major noise paths through which sound travels from outside to inside the truck. These findings were then used to develop a sound package that reduced the vehicle interior noise to meet the target. Measurements were primarily made on a chassis roll dynamometer with final road verification to substantiate the dynamometer data. Data obtained from these measurements were also used in the analytical model that predicts the impact of various acoustics parts in the vehicle, and has the capability to optimize the sound package treatment in the vehicle.

Sealant materials are used in todays automobiles for many applications such as, sealing of body seams, sealing access holes and the filling of hollow cavities. The primary reasons for these applications are to prevent corrosion, prevent water intrusion, and to reduce the noise level in the passenger compartment. However, the noise control capabilities of sealant materials have not been explored until recently. This paper discusses the requirements that a noise control material must possess, and reviews how a sealant material can fulfil these requirements. Properly designed sealant materials can possess sound transmission loss (barrier) properties, vibration damping properties over a given frequency and temperature range of interest, and often sound absorption properties with proper formulation. This paper provides case studies to substantiate the acoustical capabilities of sealant materials.

This paper discusses the importance of studying different variabilities (test and product variations) that may affect the noise reduction capabilities of automotive headliners, constructed from different materials. For this purpose, interior noise measurements were made at a position approximating the operator ear level, with different headliner materials under various operating conditions. For better understanding of the effect of different variabilities on acoustical performance, various single number values were computed from the measured data reduced in 1/3 octave band frequencies. Statistical data analyses show that the acoustical performance evaluation of headliners is affected by the product variation from one headliner to another, as well as experimental variation due to vehicle performance and test variation.