Abstract: In this paper, the linearized Euler equations (LEE) foraero-acoustics are solved using high-order Discontinuous Galerkin (DG) onunstructured grid for complex geometries. The background field, calculatedusing Finite Volume Method on structured grid, is first transferred into theLEE grid with a highly accurate method . A straightforward quadrature-freeimplementation method and parallel computing are used to accelerate thecomputation. Numerical tests indicate that very detailed features can beresolved even though high order DG was used on very coarse grids.