Over the last decade, different imaging techniques have been developed to characterize and localize non-stationary acoustic sources. This study focuses on three of them: Time Domain Holography, Real-Time Near-Field Acoustic Holography and Time Reversal Acoustic Imaging. In the first part of the paper, the principles of these three methods are reminded and the validation technique is presented. Then, the second part deals with the comparison of the results obtained with these three methods for two different kinds of sources: point-like sources (small loudspeakers) and a plate-like acoustic source emission. Advantages and draw-backs of the methods are discussed. Finally, an industrial case is studied: set-ups, measurements and analysis of non-stationary sound sources imaging are presented.