For components of ducts systems such as those to be envisaged for air conditioning system, ventilation systems for premises or enclosures (generally: whenever the installation of a fan is to be considered), for exhaust lines of combustion engine or gas turbines, etc. ... , the noise transmitted upstream or downstream of components (depending on flow direction) is not (in many cases) the only potential source of sound nuisance to consider.

Indeed, the noise radiated by the casing of components must be taken into account, because possibly impacting the soundscape of the environment whether it is a premise (e.g. in which we obviously do not want to hear the fan noise transmitted through the wall of a duct system mounted above a suspended ceiling) or whether it is the outer space (e.g. where the noise transmissions through the wall of ducts such as those of dedusting systems, or through the wall of industrial chimneys should be limited).

ITS has integrated the prediction of the sound power radiated by the casing of components of duct systems to the simulation software SILDIS (cf. acoustics simulation software).

Calculation routines have been implemented for the calculation of the sound power level emitted by components such as straight ducts and silencers (with a rectangular or a circular cross section).

Following the modification operations of the software SILDIS, the comparison of simulation results with bibliographic data (results of measurements, results of calculations by others ...) has shown a satisfactory agreement for the noise transmission of ducts and silencers casings with various geometries, constitutions and dimensions.

The expected result of improvements to the software SILDIS is an improvement of the definition of the required performance and of the sizing for soundproofing equipments such as ventilation silencers and in general: of all industrial silencers (and of their connecting parts) which design is very demanding given the sound power levels of the considered noise sources (before soundproofing) and expected performance in terms of sound insulation in the context of protection of workers, or of preservation of environment, or of improvement of the acoustic comfort in buildings.