Critical frequencies at which electromagnetic fields couple into an electronic device can be identified by comparing the power dissipation of a loaded electromagnetic reverberation chamber to that of an unloaded one. However, working conditions that ensure the required statistical electromagnetic field distribution may also imply a bad signal-to-noise ratio for the measured dissipated power. The purpose of this work is to discuss a measurement procedure and methods for data processing that, nevertheless, allow for gaining significant information from a power spectral analysis in a reverberation chamber. This comprises methods that are based on a fit of suited parametric models for the power absorption of uni- or multi-modal resonators. Their validity has been proven by simple DUTs with previously known characteristics.