The interior sound perceived in an automotive cabin is a very important attribute in vehicle engineering. Therefore, there is an industrial interest to be able to predict the interior acoustic behaviour by means of accurate simulation models. In order to understand the modelling challenges and improve the modelling know-how, experimental methods in which an acoustic characterization of the cabin is performed based on measurements play an important role. When performing an interior acoustic study, it is important to relate the acoustics responses to the intrinsic system behaviour of cabin cavity. This can be done by means of acoustic modal analysis, i.e. modal parameter estimation methods decompose the system behaviour into a set of individual resonance phenomena, each characterised by a resonance frequency, damping ratio, and mode shape. This paper will discuss the equipment requirements and advanced modal parameter estimation techniques. Specific acoustic modal analysis challenges are the high modal damping ratios resulting in highly overlapping modes with complex mode shapes and the use of a large number of references (sound sources) distributed around the cabin to get a sufficiently homogeneous sound field. The performance of Maximum Likelihood Estimation will be examined and compared to more traditional approaches.
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