Influence of air layers and damping layers between gypsum boards on sound transmission

In this paper the influence on sound reduction index of a thin air layer between gypsum board layers of lightweight partitions has been examined. It has been shown that the air layer between gypsum boards causes a decrease in sound reduction index due to mass-air-mass resonance. When the thin air layer is filled with a damping layer, the sound reduction index is increased for frequencies around the critical frequencies. Predictions show similar effects to those measured.