Sonoprobe method has been applied in non-destructive inspection of anchorage project. Its fundament is that to use dynamic transient excitation for inducing anchor bar's elastic vibration. The flaws in the bar can be estimated or deduced by determining transient response of anchor bar. Based on the theory of elasto-dynamics, in this paper, a theoretical model of acoustic detection of anchor bar has been built up. On the mechanics field, this method means that if information of disturbance resource, boundary conditions and initial conditions has been given, the dominant equation describing medium motion would be established. That is, it leads to the problem of initial value or initial boundary value of hyperbolic type or hyperbolic-diffusibility type equation. Thereby the dynamic response could be solved. As an example, analytic solution of heterogeneous wave equation is deduced in case of bounded region.