Assessment of the Performance of Trim Materials : Modeling and Validation by Mean of Several Measurement Strategies

International audienceTrim materials are designed to minimize sound transmission and maximize sound absorption. Often, a balance between those two quantities is desired with an emphasis on one or another depending on the application in hand. Porous material are typically used as they allow for both sound absorption and transmission loss while minimizing the added mass. In this paper, the performance of a melamine foam panel is assessed. The considered sample is glued on the A2-size opening of a heavy concrete cabin designed for material testing in absorption (Alpha-cabin-like) and transmission (from the cabin to surrounding environment). The material is excited through a random sound field within the cabin. The proposed work concerns the comparison and validation of several measurement techniques in order to evaluate i) the acoustic pressure and intensity maps at the test sample outer surface (radiating area), ii) the Sound Power Reduction (SPR) - assessed as the acoustic power difference on both sides of the sample, and iii) the Acoustic Radiation Ratio (ARR) - defined as the ratio of acoustic power radiated from the A2 opening with and without the sample. Amongst the selected techniques, the classical per-point sound intensity scanning (ISO9614-1) is compared to a bi-layer array of microphones and acoustic holography