Most NVH engineers are interested in the identification of vibration transmission paths such as engine mounts to effectively reduce noise in a vehicle. To identify the contribution of each vibration source and transmission path to interior noise, effectiveness( newly defined in this paper ) is calculated. Sensitivities of interior noise levels of a vehicle to force level transmitted from the engine are calculated. When the magnitudes and phases of forces due to engine vibration are changed, synthesized noise level of a vehicle is predicted on a vector synthesis diagram. It is shown that sensitivity analysis and vector synthesis can be used to predict and control the interior booming noise of a vehicle.