Simulated annealing algorithm is considered as a relatively better way of obtaining optimal placement of secondary sources in active structural acoustic control (ASAC). In this work, a baffle which is attached to the pipe subject to a harmonically excited point force or plane wave is considered. There are more than 3×107 possible combinations in this case of choosing eight actuator positions from possible 36 positions on the baffle. The performances of the simulated annealing algorithm are compared in different situations to find the appropriate parameters and updating method for this application. A set of positions which gives an overall reduction on the surface of the hemisphere within 0.3 dB of the best achievable was found through simulated annealing algorithm. Results show that the optimally placed actuators can perform better sound radiation control than the specially selected ones. The use of optimally positioned actuators can efficiently achieve structural sound radiation control.