Trailing edge noise is a major aircraft noise source which needs to be addressed if designers wish to continue their trend of making quieter aircraft with each new generation. This noise source, due to the scattering of pressure fluctuations in the wing boundary layer and near wake by the rear edge of the wing, requires extensive experimental analysis for validation of theoretical and computational models. However, experiments performed decades ago are now found to have significant flaws in their results. Modern experimental methods readily show the weaknesses in the older analysis techniques as well as limitations in newer techniques. A library of acoustic data for a NACA 63-215 Mod-B airfoil is obtained and analyzed using coherent power and beamforming techniques. Results show that the methods predict similar levels when airfoil trailing edge noise is the dominant source in the facility. When distributed background noise sources are dominant, nominal predictions do not agree, but method uncertainties become sufficiently large that exact level estimates are identified as unreliable.