In order to simulate the structural vibration and acoustic field in time domain, we discuss the calculation method of the structural damping and provide an integrated numerical method for impact sound synthesis which is finally well verified experimentally. Firstly, since the damping is considered to be one of the factors influencing the time-varying characteristics of the transient vibration, the detailed information are obtained by both of modal damping calculating methods. Secondly, the vibration and sound radiation of damping impacted plates are simulated in the time domain, showing that they are highly consistent with the results from the finite-difference time-domain method. Finally, the comparison between the impact sound of the finite cylindrical shell and the experimental results is performed, indicating that the two sounds are much the same in the temporal envelope, spectral structure and decay trend. What is more, the results imply that it is quite effective to use the these numerical methods to synthesize impact sounds.