Damping Compound

A damping compound is a viscoelastic material applied to rigid panels (plasterboard, metal, plywood) to reduce resonant vibrations and improve sound insulation. When sandwiched between two panels in a constrained layer damping configuration, the compound converts vibrational energy to heat through shear deformation. Green Glue is the most well-known brand. Damping compounds are particularly effective at the coincidence frequency, where a single panel’s transmission loss drops due to efficient radiation. By adding damping, the coincidence dip is reduced by 5–15 dB, significantly improving overall STC rating. Application is straightforward: the compound is spread on one panel, and a second panel is screwed over it. The system is effective across a broad frequency range (100–5000 Hz). Damping compounds are widely used in retrofit sound insulation projects where cavity depth is limited and in purpose-built studio and cinema constructions.