In diagnostics, the condition of mechanical systems can be determined very reliably on the basis of noise. Noise source visualization is based on a number of different methods. These methods are primarily intended for a specific noise source in a specific acoustic environment. In this paper, a visualization method of complex noise sources, based on the use of acoustic camera, is dealt with. All types of different complex noise sources can be visualized, using a special acoustic algorithm. Also, various transient acoustical phenomena can be observed.