Theoretical analysis method on a sound radiation from plates deals with only typical vibration states like as piston vibration, modal vibration and diffuse vibration. In this paper the numerical calculation method newly developed on acoustic radiation impedance is presented. This is a discrete method, that is, the vibrating plate is imaginariry divided into the discrete parts and those are dealt with as individual sound sources. This method can be then applied to every vibration states of the plates and also suits for in situ measurement. The influences on the sound radiation impedance of vibrating points, size of plate, boundary condition, damping coefficient and stiffeners are investigated using this method. Furthermore, acoustic radiation characteristics of concrete slabs under diverse conditions are shown.
