Taking into account the interactions between porous media for the sizing of multilayer acoustic structures is still a subject of questioning for specialists in Research and Development in the acoustics sector.

Porous media are the basis of most of multilayered acoustic structures generally used to form many products and construction systems for applications related to noise control: soundproofing panels, absorbing linings, dissipative silencers, etc ...

The feature of some porous media is to absorb sound (rock wools, glass wools, polyester wools, foams, etc ...). The feature of other porous media is to protect previous ones (without degrading their acoustic performance) with respect to agressions related to possible shocks (e.g. in case of soundproofing panels, absorbing linings, .. .) or with respect to agressions linked to the existence of hostile environments because of high temperatures and / or aggressive effluents and / or high gas flow speeds (e.g. in the case of dissipative silencers).

ITS has improved the way for taking into account the interactions between porous media for the design of multilayered acoustic structures with the simulation software SILDIS®.

Improvements in computational routines focus on the modification of models implemented to take into account the influence of covers or of perforated protections with respect to absorbing linings that are positioned at the rear.

Following the changes, the comparison of simulation results with bibliographic data (results of measurements, results of calculations by others ...) has shown a satisfactory agreement for the normal incidence absorption of various acoustic structures.

The expected consequence of the improvements to the acoustics calculation software SILDIS® (for taking into account the interactions between porous media for the design of multilayered acoustic structures) is an improvement of the accuracy of the sizing of high-tech soundproofing equipment such as silencers for very large industrial fans, silencers for exhaust or air intake of combustion turbines, etc ... whose design (involving multilayered acoustic structures with specific porous media) is very demanding given (on the one hand) mechanical and aerodynamic constraints to be accounted and given (on the other hand) sound power levels of considered noise sources (before soundproofing) and expected performance in terms of sound insulation in the context of protection of workers and / or preservation of environment.