Sound Radiated From Multilayer Trim Components

Lightweight porous acoustic multilayer trim components have traditionally been specified in terms of sound absorption and sound transmission loss performance targets. These targets are valid for airborne noise excitation only, in the medium to high frequency ranges. Unfortunately, this neglects the fact that in real-world vehicle applications, these components are also subjected to low-medium frequency structural vibration inputs from mechanical components, which is typically an acoustic sound radiation problem. Importantly, the material specification of the trim component developed only for absorption and sound transmission loss may be sub-optimal in terms of sound radiation behaviour. This then highlights the necessity for additional focus on this topic, especially from a numerical simulation perspective in the early stages of the sound proofing development process. The appropriate low-medium-high frequency acoustic performance balance can then be obtained. Simulation methods are now well established for predicting the absorption and sound transmission loss of multilayer trim components including lightweight porous materials and surfaces, but are less well developed for the prediction of the multilayer sound radiation problem.