In this paper the problem of estimation of parameters of a mechanical system using sampled impulse response data is considered. For the estimation of the unknown parameters the modified Prony method is used. It is shown that for the particular data the use of multiple poles improves the accuracy of the model. The initial Prony method estimates are further optimized by an iterative Levenberg optimization procedure. The root mean square error (RMSE) is the criteria for the estimation procedure. The additional modes are used in order to get better results.