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At certain key stages in the vehicle development process, prototype vehicles are available for NVH testing. This testing fulfills two functions: primarily it is used to assess the status of the vehicle to the program NVH performance targets, but it also provides an opportunity to validate the vehicle SEA model. These single vehicle test events provide a snapshot of the NVH performance but do not provide any understanding of the variability of the NVH performance, which is due to many factors: components, build or assembly and test setup variability. SEA models can be used to estimate the vehicle level variability, if the variability of the interior components is understood, but there is limited data available to confirm the accuracy of these predictions. In this paper we examine the repeatability and reproducibility through a standard gage R&R study of Engine Noise Reduction (engine NR) and Tire NR testing.

Interior noise has become a significant performance attribute in modern passenger vehicles and this is extremely important in the luxury market segment where a quiet interior is the price of entry. With the elimination of early prototype vehicles to reduce development costs, high frequency analytical SEA models are used to design the vehicle sound package to meet targets for interior noise quality. This function is important before representative NVH prototypes are available, and later to support parameter variation investigations that would be cost prohibitive in a hardware test. This paper presents the application of an analytical full vehicle SEA model for the development of the acoustic package of a cross over luxury utility vehicle. The development concerns addressed were airborne powertrain noise and road noise. Power flow analysis was used to identify the major noise paths to the interior of the vehicle.

As customer awareness of product sound grows, the need exists to ensure that product sound quality is maintained in the manufacturing process. To this end in-process controls that employ a variety of traditional acoustical and alternate sound quality metrics are utilized, usually partly or wholly housed in a test enclosure. Often times these test cells are required to attenuate the background noise in the manufacturing facility so that the device under test can be accurately assessed. While design guidelines exist the mere size and cost of such booths make an iterative build and test approach costly in terms of materials as well as engineering and testing time. In order to expedite the design process and minimize the number of confirmation prototypes, SEA can be utilized to predict the transmission loss based upon material selection and booth construction techniques.

In this paper the application of Statistical Energy Analysis (SEA) to the sound package design for a fuel cell powered sedan is presented. Fuel cell vehicles represent a different challenge to a vehicle with a conventional powertrain. With the replacement of the internal combustion engine (ICE), a principal source of airborne and structure-borne powertrain noise, the expectation is that the cabin noise levels would be significantly reduced as the main noise sources would be road and wind noise. A fuel cell powertrain, however, has a number of mechanical sources on the body structure that will radiate airborne noise and may transmit significant structure-borne noise to the vehicle interior. With this alternative power train, much of the conventional wisdom on vehicle sound package developed from experience with ICE's must be reconsidered.

For the assessment of vehicle acoustics in the early design stages of a vehicle program, the use of full vehicle SEA models is becoming the standard analysis method in the US automotive industry. One benefit is that OEM's and Tier 1 suppliers are able to cascade lower level acoustic performance targets for NVH systems and components. Detailed SEA system level models can be used to assess the performance of systems such as dash panels, floors and doors, however, the results will be questionable until test data Is available. Correlation can be accomplished with buck testing, which is a common practice in the automotive industry for assessing the STL (sound transmission loss) of vehicle level components. The opportunity to conduct buck testing can be limited by the availability of representative bodies to be cut into bucks and the availability of a transmission loss suite with a suitably large opening.