Truck cab structures usually consist of plates, shells and beams. The traditional methods of structural modification of cabs to reduce the noise include adding mass and damping materials to the cabs and changing panel thickness of the cabs etc. These methods are somewhat blind when the optimal improvement positions are not yet known. In this paper, the MATV technique is used to determine the dominant panels, which have large contribution to the noise level, on the side of drivers right ear. Then, the BEM acoustic sensitivity analysis is utilized to search the positions of the structure which have the dominant influence on the specific sound pressure level. Using this method, the structure can be well improved for noise control.