The present invention relates to a conditioning method of gas turbine engine components (e.g. compressor blades and vanes) for aerodynamic noise reduction. The gas turbine engine components are plasma treated in a high vacuum environment to generally reach a surface roughness (Ra) below 150 nanometers and in some cases below 25 nanometers. Then during the same process the components are coated using either a metallic or ceramic, hard, thin coating ranging from 100 to 3000 nanometers in thickness depending on desired surface smoothness and non-fouling properties. The same treatment combined with a surface relaxation process, which is part of a smoothing process, allows applying even up to 100 micrometers of hard coating without changes to high cycle fatigue properties and overall performance. Improved surface smoothness of the components and enhanced non-adhesiveness of the contaminants advance the quality of the flow through the gas path and compressor aerodynamic noise reduction.