Verification of a New Sound Power Measuring Method and Application to Vehicle Component Testing

The determination of the sound power is defined in various ISO standards, which are based on different measurement procedures and environments. For example, the ISO 3741 describes the determination in a reverberation room, or the ISO 9614, which describes the determination based on sound intensity measurements on a pre-defined surface. For a less time-consuming and more cost-efficient measurement conduction, the IPEK - Institute of Product Engineering developed a new method for the sound power determination, based on sound intensity measurements on a free-form measuring surface. It has been shown previously, that this method delivers consistent results for omnidirectional sources, regardless of the shape of the measuring surface. However, these results need to be further verified by the aforementioned different standardized procedures, as well as for using different types of sound sources. Furthermore, the new method is to be applied on vehicle components, in order to efficiently quantify their respective sound power. In this paper, the measurements and analyses for the verification of the developed method, as well as further applications are presented. The verifying measurements are conducted in different environments, such as a semi-anechoic chamber and a reverberation room as well as using different sound sources like a dodecahedral speaker and a volume velocity source. Moreover, different measurement instrumentation, like free-field microphones and a 3D sound intensity probe are used. Subsequent to the verification, the method is applied on acoustically dominant components of a vehicle on a roller test bench. This enables an estimation of the acoustic contribution of vehicle components to the complete vehicle, which can be used for an earlier evaluation in the vehicle development process.