Aircraft noise research is a key area of focus in DLR’s aviation research program and serves the purpose of reducing noise induced by air travel. This is coherent with respective politics at European level. The well-known strategic paper “European Aeronautics: A vision for 2020” of the European Commission demands halving the perceived noise per operation with respect to the year 2000 status, i.e. a reduction of about 10 decibels. In the follow-up of the paper, called “Flightpath 2050”, this objective appears even increased to 15 dB. The assessment of the current status and the target achievement is mainly based on predictions rather than measurements. The latter exists for engine noise and take-off but reliable data on airframe noise in the approach and landing phase is missing. Whereas new development and market entry often takes decades for newly designed quieter aircraft, noisereducing modifications offer short or mediumterm prospects for change, and can take effect much more quickly. This is what makes the LNATRA project so important. For the project the following targets were defined. First, the noise reduction potential by means of retro-fitting an aircraft shall be demonstrated. Second, both the engine and airframe noise shall be reduced by about 4 EPNdB (Effective Perceived Noise Level) which is a very ambitious target. The Institute of Aerodynamics and Flow Technology is leading the project in cooperation with the Institute of Propulsion Technology and contributes to the project by the selection and design of noise reduction technologies, the aerodynamic qualification of all means and the final measurement and assessment of the achieved noise reduction.