In this paper, we present the inverse analysis for identification of the cavity position and the cavity size in structures. The performance function is defined by square sum of residual between the observed and the computed sound pressure. Here, the observed sound pressure is measured by the microphone in the experiment of hammering test. The problem is to find the cavity position and the cavity size so as to minimize the performance function. The formulation for this problem is carried out by the adjoint variable method, and the numerical simulation of the sound pressure propagation is carried out based on the wave equation and the finite element method. In addition, the identification of the cavity position and the cavity size is also carried out based on the adjoint variable and the finite element methods. The hammering signal is also identified by the observed sound pressure. To do that, it is important how to give the initial condition of the cavity position and the cavity size. In this study, the result of the clustering based on the self-organizing map is employed to determine the initial condition of the cavity position and the cavity size. The identification of the cavity position and the cavity size for a partial problem is shown in this paper.
