Three vibro-acoustic analysis using Finite Element Method (FEM) is presented. The first analysis is a three-dimensional (3D), interior acoustic, vehicle cabin model, where the modal density and natural frequencies are discussed. The second example is a bi-dimensional (2D) fluid-structure model of the vehicle cabin. In this analysis the main results of the coupled free vibration analysis are presented and discussed. The third example illustrates the use of DtN (Dirichlet-to-Neumann) Map, for exterior acoustic analysis. The DtN Kernel for two dimension problem is presented, and the finite element form is derived. A simple bi-dimensional problem of acoustic radiation from the propulsion system is obtainned.