An apparatus and method is provided for attenuating aerospace engine noise and unsteady pressure fluctuations associated with high velocity exhaust flows. The apparatus and method reduce acoustic fatigue damage to aerospace vehicles that may be caused by the reflection of exhaust energy from landing and/or launch platforms. The apparatus includes a passive treatment area associated with the platform operable for reducing the magnitude of the reflected sound waves and unsteady pressure fluctuations from the high velocity exhaust mass flow exiting from the engine. The passive treatment area may include a layer of sound absorptive material, at least one set of roughness elements for disrupting high velocity flow structures. A protective cover may be positioned over the passive treatment area for permitting exhaust flow to pass therethrough while still providing adequate structure to support the weight of the aerospace vehicle.