Straight ducts are components which are often present in duct systems such as those to be envisaged for air conditioning system, ventilation systems for premises or for enclosures (in general: each time the installation of a fan is to be envisaged), exhaust lines for thermal engine or gas turbines, etc ... for which they are (among others) the basis for the construction of stacks.

The acoustic performance of straight ducts must be accounted for the purpose of the design of equipments for which noise transmission either at extremities of the duct system or through duct wall of the components of the duct systems must be limited.

ITS has integrated the prediction of the acoustic performance of straight ducts to the simulation software SILDIS (cf. acoustics simulation software).

Calculation routines have been implemented for the calculation of the insertion loss (attenuation) and of self noise of those equipments (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 straight ducts with various geometries, constitutions and dimensions.

The expected result of improvements to the software SILDIS is an improvement of the accuracy of the definition of the performance required 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.