In order to construct an evaluation method for structure-borne sound in building floor slabs, the dynamical analysis method for floor slab vibration in audio-frequency ranges and the numerical calculation method for sound radiation produced from slabs have already been developed. In the present paper, the heavy weight floor impact sound is numerically calculated by generalizing these developed methods, and the effectivity of this simulation method is shown. The vibrational characteristics of the diverse floor slabs and the stiffening effects of beams in particular are also clarified using this method