Thermoacoustic engines convert thermal energy into acoustic work with the distinct merits of simple configuration, potentially high efficiency, no moving parts and no harm to the environment. In order to take full use of low grade thermal energy, it may be an effective approach to decrease further the onset temperature of thermoacoustic engines. This paper proposes a new method to decrease the onset temperature of thermoacoustic systems by introducing a pressure disturbance. The feasibility has been experimentally verified on a self made hybrid thermoacoustic engine. Experimental results show that the pressure disturbance can significantly decrease the onset temperature of the engine. For example, with nitrogen of 0.91 MPa filled in the engine, the onset temperature of 219 degrees C without the pressure disturbance decreases to 193 degrees C with the disturbance. Furthermore, the influence of the pressure disturbance on the dynamic onset and damping processes has also been investigated and compared with conventional ones. The results will be helpful for further understanding of the onset mechanism of thermoacoustic engines and to commercialize the engine by using low grade thermal energy. (c) 2005 Elsevier Ltd. All rights reserved.