Measured effect of resilient edge joints on airborne sound insulation of heavyweight wall

Abstract

It is common assumption that resilient joints around a heavyweight construction improve sound insulation between adjacent rooms. Effect of resilient joints on sound insulation has not been studied sufficiently. This study investigated how the joint resiliency around a heavyweight wall affected sound reduction index (SRI) measured directly through the construction. A calcium silicate block wall was built three times in a laboratory using three different joint types A−C between the wall and the building frame: A) all four edge joints rigid, B) three resilient and one rigid joint, C) all four joints resilient. SRI was determined for A−C. Total loss factor (TLF) was determined for A−C by measuring structural reverberation time using hammer impact stimulus. SRI reduced, remarkably, with increasing level of joint resiliency. For joint type A Rw was 50 dB while it was 45 dB for B and 43 dB for C. Correspondingly, TLF reduced with increasing level of resiliency. The effect of joint type was evident above the critical coincidence frequency 185 Hz of the wall. Resilient joints prevented the sound transmission to the building frame, which increased sound radiation to the receiving room. Therefore, heavyweight wall should be mounted to surrounding heavy constructions using rigid joints.