In Statistical Energy Analysis (SEA), the sound field in an acoustic subsystem is assumed to be diffuse and reverberant, that is, there is an equal probability for a wave to travel in any direction with equal wave intensity. Although this has proven to be an efficient way of modeling the interior space of a vehicle , it is less suitable for external cavity modeling. The main reasons include: a) high directivity pattern of sources such as tire/road noise, b) grazing angle of incidence of sound waves on some vehicle panels and c) shadowing effects resulting from the geometry of the vehicle. This shadow effect can be modeled in an SEA model in order to account for the geometry of the vehicle and any change in direction of the acoustic wave field. This paper addresses the latter by proposing a new modeling technique that corrects the coupling loss factor (CLF) of exterior acoustic subsystems based on vehicle geometry. The method presented is also validated with experimental data measured in a semi-anechoic chamber. Correlation levels suggest that this technique is an effective way to model the external vehicle sound field and is a good addition to other widely accepted SEA modeling techniques.
2004 – INTERNOISE, Prague, Czech Republic
Denis Blanchet (ESI Group, USA)
Rich DeJong (Calvin College, USA)
Kazuki Fukui (Nissan Motor Co., Japan)