THE EFFECT OF DAMPING IN RESILIENT MATERIALS USED IN FLOATING FLOORS ON IMPACT SOUND INSULATION

Resilient materials are nowadays widely used as underlayers in floating floors, in order to reduce the transmitted impact sound pressure level. A floating floor, i.e. a floating slab on a resilient support applied on the structural base floor, behaves as a classical mass-spring damping system and its motion is analytically described in terms of the Newton's second law. As a consequence, because of the resilient nature of the supports, the coupling of the vibration field of the floating slab to the structural base floor depends both on the resonance frequency and dissipative effects. As shown in this paper, the internal damping of resilient materials plays a role in insulation of impact sound, by varying the slope of the attenuation curves. As a matter of fact, the spectral distribution of energy transmitted through a mass spring -damping system strongly depends on elasticity close to the resonance frequency of the system, but depends also on damping at higher frequencies.