Acoustic Emission (AE) testing is an advanced non-destructive testing (NDT) technique that measures stress wave, or ultrasonic waves, that are generated by active flaws. AE testing is a passive technique that analyzes the stress waves emitted by structural defects activated during loading. Some common examples of AE in materials include fatigue crack growth in steel pressure vessels and fiber breaks in composite materials. The sudden release of energy caused by these phenomena generates elastic waves that propagate through the volume of the material and guided by the boundaries of the material. AE may travel through the bulk of a material as longitudinal and shear waves. Along the boundaries of the material, AE can be detected via measurement of guided and surface waves. Typically, stimuli such as mechanical loads, pressurization, thermal stresses and magnetic forces, can produce AE.