Acoustic emission (AE) analysis is a useful method for tracking the course of damage development in fiber reinforced composites. The analysis of the AE data is simple as long as the AE measurement is only used as an indicator that there is something going on in the material. Further analysis of AE data with respect to location and characterization of the AE sources must take into account the effects of the sample geometry. For unbounded media where bulk waves dominate wave propagation, AE sources can be located by determining arrival times at different sensors [1] and characterized by applying moment tensor inversion techniques [2]. However, components and laboratory test coupons are thin-walled in most cases and the analysis methods described above usually cannot be applied. In such samples, wave propagation in the far field is dominated by guided wave modes which show dispersion. During the past two decades many investigators have tried to classify the different source mechanisms in bounded samples by using simple parameters (like maximum amplitude, rise time, energy, counts or duration) extracted from waveforms. The reported data (see e.g. [3–7] and references therein) are highly inconsistent because the measured parameters depend of course not only on the AE source characteristics but also on the specimen shape and material.