In this research, radiation noise from a cylindrical shell is estimated by a virtual microphone in a wide-frequency band. So far, active strucural acoustic control of cylindrical shells based on radiated modes has been carried out fora specific frequency of the system. That is, considering the desired frequency (for noise cancelation), radiated noise is controlled. However, in this research, we tried to do this for a broadband frequency range. Therefore, state equations are extracted for active control of the system. For controller design, the output matrix must be independent of the system frequencies; if this matrix is ??related to the system frequencies, we cannot determining system parameters for a wide-frequency band, consequently, we cannot control the system. Four methods may be available for solving this problem. These four methods are averaging, selecting the basic radiation modes, system identification and switching the vibrating mode to the acoustic mode by converting to the transfer function. In this study, the last method is used (switching the vibrating mode to the acoustic mode by converting to the transfer function). The results of this method is used for a low number of longitudinal and transversal modes and their results are used to design the controller and active control system Acoustic pressure, control force and accelerations graphs are iullestrated. It can be observed that using the proposed method, the acoustic noise of cylindrical shell at a specific frequency as well as wide-frequency band can be minimized. Keywords: Active Structural Acoustic Control, ASAC, LQG, Piezoelectric, Cylindrical Shell, Active Control