A technique is developed which utilizes numerical models and in situ measurements to characterize acoustic fields and identify noise sources. The numerical model is based on boundary element numerical procedures and is used to characterize the acoustic cavity. Passive boundary conditions in the form of impedance boundary conditions are used for the numerical model. The sound field is found by measuring several pressures in the acoustic field and using the data to overdetermine the numerical problem and solve for the complete sound field. The model can then be used to identify acoustic energy paths in the field. The model can also be used to evaluate design alternatives.The method has been tested analytical and verified. In addition, the sensitivity of the method to error in the impedance data or measurement data was tested and found to be acceptable.