The interaction between the ISO tapping machine and light¬weight floors

The ISO standard tapping machine, used as an excitation source in rating the impact-sound level of a floor structure, interacts with the floor structure during the hammer impact. Expressions for the force spectrum due to the impact are presented. The 6 dB difference at low frequencies of the force spectrum, evident in measurements, and reasons for it, are discussed. The interaction is nvestigated by use both of simplified lumped models and arbitrary frequency-dependent models. Local effects due to indentation near the point of impact and to global effects due to stiffeners are included in the description of the mobility involved. Numerical results are presented, where it is concluded that both the local and the global effects of the driving-point mobility are important in describing the force spectrum caused by the interaction between the tapping machine and the complex floor structure.