An efficient finite volume approach has been used to develop a three dimensional Helmholtz acoustic solver for complex geometries. This acoustic solver was utilized to obtain characteristic mode shapes and frequencies of a baffled combustion chamber. An experimental setup, including stationary and moving sensors, has also been used to measure these quantities for the same model combustion chamber. Although each of these methods has certain limitations, combination of the numerical results and the experimental data provide a capability to identify complicated acoustical fields created by the combustor complex geometry. Using this approach the effects of the nozzle convergent section and the number of radial baffles on the chamber’s dominant acoustic modes were investigated. It has been shown that acoustic solver is capable of capturing major effects caused by the presence of radial baffles and combustor nozzle geometry; however radial baffles may produce nonlinear effects that cannot be captured by a Helmholtz acoustic solver.