In diagnostics, noise can be a very reliable way of defining the condition of mechanical systems. There are different methods to visualise the noise source. Primarily, they deal with a specific noise source in a specific acoustic environment. This paper presents a visualization method of complex noise sources, using an acoustic camera. This method makes it possible to visualise all types of different complex noise sources; a special acoustic algorithm is applied for this purpose. Also, it is possible to observe various transient acoustical phenomena.