A 2.75D model for the prediction of noise inside buildings due to train traffic.

Structural borne noise generated in building, by train, subway, tramway... is a rising topics due to urban densification and to the amount of new transportation project. That's why it's one of CSTB huge subject of R&D since more than ten years. It's also why we have decided, two years ago, to start to give acoustician access to our numerical tools on this topics: MEFISSTO

Here is a great paper from our Researcher Philippe Jean, MEFISSTO father, in the last ACTA ACUSTICA (Nov. 2018), on one of the last development of the software.

You can request the full text on Researchgate. See the abstract here:

An existing 2.5D FEM-BEM model is extended to predict sound pressure levels inside buildings. Previous studies have showed that a 2D approach lacks precision. The 2.5D model will approximate volumes as infinite ducts. By introducing a 3D modal-based acoustic model of the volumes, the proposed approach will be one step closer to the full 3D reality. The mixing of 2. 5D and 3D models has been named 2.75D. Two different ways to compute sound radiation are proposed: an energy radiation computation or a 3D modal approach. A comparison of 2.75D and 3D computations has been done in the case of a simple building parallel to the tracks. The validity of this simplified approach is discussed. Last, the engineering approach proposed in the European project RIVAS is compared to the 2.75D model.