Effect of the mass-spring resonance of a slab covered with carpets on the sound insulation performance

Abstract

It is well known that the overall sound insulation performance between two adjacent rooms in actual buildings is not so much increased even if a high spec wall is used for the partition because of several flanking sound transmission paths. In recent years, the phenomena that a slab covered with carpets increases the sound transmission through the floor have been found. This is caused by the resonance with the mass of the carpets and the spring of those underlying materials, and consequently the sound insulation performance significantly decreases in the mid-low frequency range. The resonance frequency can be shifted to higher frequencies using formed plastic sheets of higher stiffness for the underlying materials. Although this would usually be one of countermeasures to increase the overall sound insulation performance, it is not a fundamental solution for noise control engineering. In the present work, in order to control the mass-spring resonance itself, a method of focusing on permeability of the carpets is proposed. The resonance is expected to be damped with the flow resistance, which is caused by setting an appropriate permeability. It is theoretically investigated using a simple model, and an experimental validation is also carried out.