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High frequency responses of structural-acoustic systems may be predicted by statistical energy analysis (SEA) or energy finite element method (EFEM). To combine the good features of these two techniques, a simplified energy finite element method, referred to as EFEM0, has been developed recently. The EFEM0 technique, which is compatible with SEA, integrates the joint coupling procedures for discontinuous systems and the finite volume formulation for continuous system. The EFEM0 models have been verified either analytically or experimentally for one- and multi-dimensional systems. In this study, the EFEM0 technique is applied to a passenger van for a noise control investigation. The general scheme is to incorporate the EFEM0 coupling factors into a SEA model in order to release some SEA assumptions and improve the SEA model, especially for relatively high damping, strong coupling and direct field cases.

When characterizing absorption in vehicles, a knowledge of the in situ performance of the acoustical absorbers is often desired. To measure this is a relatively easy task in a large diffuse sound field. However, inside a vehicle where the sound field is not diffuse, the measurement is more difficult. Impulse and interrupted noise techniques have been used to measure absorption inside cavities with extremely short reverberation times. Among several difficulties associated with these techniques are the response time of the filters and the influence of the averager in the instrumentation. In many cases, these limitations make these traditional techniques impractical for use in a vehicle. With the advent of modern digital signal processing, however, there are a number of other readily accessible techniques that are more useful.