Optimisation of noise reducing device intrinsic performances

The work presented in this paper is part of the QUIESST European project, in which one of the objective is to perform optimisations of noise reducing devices. We present here optimisation results concerning the intrinsic performances of noise barriers. First the limits of these optimisations are determined: this concerns geometrical limitations as well as limitations on the number of materials. The intrinsic performances under interest are calculated using numerical simulations (the Boundary Element Method and the Transfer Matrix Method) in such a way that calculated values are as close as possible to quantities that one could measure using the CEN/TS 1793-4 -5 -6 standards. These simulations lead to reflection, transmission and diffraction performance values, which are expressed as a relative gain (or loss) to a reference noise barrier. The multi-objective optimisation strategy is then detailed and applied to nine coherent noise reducing device families. It is shown that using a specific set of parameter...