The design of a rocket launch environment is a highly complex multi-objective task and the acoustic part of this process is very important, as the noise produced during a launch can affect both external and internal systems. In this study, a numerical analysis of the acoustics of rocket plumes impinging perpendicularly on a flat plate is performed. A Detached Eddy Simulation code is used to calculate the flow field, while a Computational Aeroacoustics code, based on the Ffowcs Williams and Hawkings method is used to extend the flow field results to the near and far-fields. The impingement of the rocket plume creates complex flow phenomena, resulting in many different noise sources. While these noise sources include sources similar to those seen in free-jets, other noise sources that are unique to impinging jet cases are also observed. These unique noise sources are created by the interaction between different flow structures and between the acoustic waves and the flow structures. This study aims to establish a better understanding of these noise sources, while proposing a method to decrease the noise levels both in the close proximity of the launch vehicle and in the far field. A wall with a circular cut-out is introduced between the nozzle exit and the impingement wall, to block the acoustic waves traveling upstream from the impingement area towards the launch vehicle. The effects of the placement of the wall and the radius of the circular cut-out on the noise levels are investigated. The research shows that the introduction of a wall with a circular cut-out creates new acoustic sources that have high frequency nature and are directed in the upstream direction. It is also observed that the best attenuation is achieved in the far-field and the near-field when the cut-out is as close as possible to the jet flow without causing any disturbances to the flow itself.