2. Vibration and Sound Radiation

In this chapter, we discuss the general structural–acoustic problem. Before we begin to investigate the active control of structural–acoustic system, it is important to review some of the basic theory of structural–acoustics and the coupling between vibrating structures and the radiated sound field. The dynamics of continuous systems (such as beam and plate) is the focus of this chapter. Firstly, the structural modes and natural frequencies for beam- and plate-type structures are presented. The results will be used in the analysis and design of active control of vibration and sound radiation from these structural types throughout this book. Secondly, by using the Fourier transform, the sound pressures and sound powers of the vibrating structures are discussed in the wave-number domain. Finally, the calculation of sound power by using radiation mode approach is presented. Additionally, some information for several basic commands from GUI, which are used in the design of the interface of the program used throughout this book, will be given in this chapter. It is hoped that this chapter serves as a tutorial introduction not only to structural–acoustic analysis but also to the use of MATLAB and GUI.