Rectangular ducts and circular ducts are the basis for many products and construction systems for applications related to soundproofing: dissipative silencers, resonant silencers, etc ... . They also form the connection pieces which are often implemented on the occasion of the installation of silencers in ventilation systems for example.

The sound attenuation of the wall of such ducts must be taken into account for the design of equipments for which noise transmission through the envelope they are (for soundproofing equipments) or through connecting ducts of the latest must be limited.

ITS has integrated the computation of the acoustic performance of rectangular ducts and of circular ducts wall to the simulation software SILDIS (cf. acoustics simulation software).

Calculation routines have been implemented for the calculation of the transmission loss of those equipments (for circular ducts: either spiral wound or not).

Following the modification operationsof the software SILDIS, the comparison of simulation results with bibliographic data (results of measurements, results of calculations by others ...) has shown a satisfactory agreement with regard to the transmission of noise through ducts with varied geometries, constitutions and dimensions.

The expected result of improvements to the software SILDIS is an improvement of the accuracy of the sizing of 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.