To explore the effects of Gedeon streaming on the onset and damping behaviors, infrared imaging is applied for the first time in a traveling-wave thermoacoustic engine to observe the temperature evolution of the regenerator. Under conditions of with and without Gedeon streaming, the temperature distribution differences of the regenerator in the onset and damping processes are compared and analyzed. Based on the visual images, the dimensionless temperature distribution reveals some phenomena that have not been revealed by traditional measurement methods. Analysis of the thermal and mass flows is made to further understand the mechanism of the onset and damping processes. (C) 2011 Elsevier Ltd. All rights reserved.