Although AE has been commonly used since antiquity, its scientific application emerged in the 50s where, for the first time, systematic experiences were performed in tensile tests. This discipline experienced a quick development during that decade, only as a non destructive testing technique, but certainly with much more advantages, as AE allowed to detect and locate active fissures.
Later on, its use became more relevant and today we can confirm that, during the last decade, its applications have been enhanced to other areas and materials. At present, it is not easy to find a material which has not been tested using this technique. Its applications range from coating characterization and leakage locations to traditional fissures detection and location. AE is applied in medical and tool machinery; in the latter, the state of the tool can be determined by detecting the signals generated by wear. During the last years, a great number of works on cement and composite materials have been published. However, in spite of the valuable contribution that AE technique can provide, its application in our region has not been widely spread.