This paper is devoted to development of analysis methods of acoustic emission (AE) signals during the destruction of structurally inhomogeneous materials. A porous iron sintered powder PZHRV2 is used as a model material. Materials of this type are typical materials with inhomogeneous structure. They contain two «components» with significant differences in their physical and mechanical characteristics. The first component consists of compact areas, and the second is a pore space. Porosity of the samples is between 5% and 25%. A new approach to classification of acoustic emission signals is proposed. The flow of AE acts is separated into groups in accordance with different parts of an amplitude distribution. Allocation of these groups corresponds to physically different mechanisms of deformation and fracture of materials — plastic deformation of the compact areas of material and growth of cracks. Allocated contributions to the total acoustic emission are estimated. They described the accumulation of damage caused by various sources of AE in the material.