A computational aeroacoustics approach is applied to studying sound propagation in subsonic and supersonic nozzle.The spatial derivatives are discretized by DRP scheme

and the low dissipation and dispersion Runge Kutta scheme is used for time integration.The Giles' characteristic 1D unsteady non reflecting boundary conditions are applied to the inflow and outflow boundary regions.Numercial results agree well with analytical solutions and it reveals that the DRP scheme performed very well because of the high resolution and robust stability and is capable of calculating sound propagation.