As a continuation of the previous work, this paper deals with an investigation into the direct frequency response of a coupled acoustic-structural system and its sensitivity. If one tries to determine the direct frequency response of a coupled system using a conventional analytical technique, it may result in poor calculation efficiency for certain systems. An iteration method is proposed here that does not employ an inverse matrix (or triangular resolution) of the impedance matrix of coupled system. An algorithm is then derived for calculating the corresponding frequency response sensitivity. It is demonstrated that the use of this algorithm reduces the calculations and makes it possible to determine the frequency response and sensitivity with good accuracy.