Kletschkowski T., Sachau D., Drenckhan J., Gleine W.

Nowadays, several noise source localization techniques have been established to detect acoustic hot spots. The selection of the right method depends on the information required, as well as on the application. The methods range from simple sound pressure measurements to more advanced methods as Beamforming and Inverse Boundary Element Method (IBEM). However, many localization techniques have the drawback, that they are only applicable in free-field conditions. For this reason, measurements in interiors are often conducted by creating artificial free-field conditions. In order to avoid this problem – caused by standing waves – a novel approach has been introduced in order to detect acoustic hot spots using the Inverse Finite Element Method (IFEM). This method has the advantage, that it can easily be applied to identify sound sources in interiors without creating artificial free-field conditions. It is therefore well suited for interior noise problems. The approach – presented in the paper – is based on a FE-Model of the interior sound field in the frequency domain. This model has been applied to predict the sound pres-sure distribution in the interior by a standard FE-Simulation. Data taken from a certain subspace of the interior – called measurement area – have been used afterwards as boundary conditions for the IFEM that have been applied to recalculate the original sound pressure distribution at the interior boundary. In order to verify this numerical procedure, an experimental setup consisting of a barrel with nine loudspeakers mounted at the circumference has been build up. This setup is capable to create various sound fields within the barrel by activating different sets of speakers. A vibro-acoustical modal analysis has been performed to verify the system dynamic, predicted by FE-Simulations. In contrast to previous publications this has been the first step to apply the IFEM to lifelike interiors.