An acoustic investigation is one of the most important tasks during the design of a rocket launch vehicle, since near-field acoustic loads can be detrimental to the launch vehicle itself and far-field acoustic levels have a high impact on noise pollution around the launch site. In this study, the effect of a noise reduction method applied to a supersonic jet impinging on an inclined flat plate is investigated. Similar noise sources that are present in free-jet flows are also observed in impinging jets. However, the introduction of an impingement plate creates new acoustic sources. These sources are created by the impingement of the jet flow and the interaction of the acoustic waves that are created in the free-jet region with the impinging flow. The goal of this study is to gain insight into the acoustic sources that are present in a jet impinging on an inclined flat plate, while trying to attenuate the near-field and far-field noise levels by introducing a wall with a cut-out between the nozzle exit and the impingement plate. The aim of this strategy is to block the waves traveling upstream towards the launch vehicle as much as possible, containing the waves between the impingement plate and the wall with a cut-out. The effects of the location of the wall and the size of the cut-out are investigated by analyzing different setups, while trying not to disturb the flow significantly, as this would create new noise sources. The flow field is calculated by a Detached Eddy Simulation code and 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.