Flow and acoustic-fields of a supersonic jets impinging on an inclined flat plate and arc plates are computationally analyzed toward the prediction of the rocket plume acoustic waves at the rocket fairing. Effects of angle and curvature of plates on the acoustic-field are investigated in detail. A weighted compact nonlinear scheme is employed and three- dimensional compressible Navier-Stokes equations are solved. The results show that two acoustic waves generated by the interaction of shock and shear layer in the vicinity of the jet impinging affect the magnitude of sound pressure level near the fairing of the rocket in the case of the flat plate The plate angle greater than 55 degree significantly reduces the sound pressure level at the rocket fairing. Over-all sound pressure level becomes larger when curvature of the arc plate increases in the case of the arc plate because of change in directivity of acoustic waves.