In order to reduce rotor-stator interaction noise on future high-bypass engines, silent Outlet Guided Vanes (OGVs) have to be designed. This study focuses on noise predictions by means of weakly compressible and compressible lattice Boltzmann simulations, along with aerodynamic assessment. Computations are performed on a full test rig including a grid generated turbulence interacting with a seven vanes rectilinear cascade as in the test campaigns at Ecole Centrale de Lyon. Moreover, the noise reduction achieved by two passive treatments proposed by Onera, which are based on leading edge serrations, is evaluated.