Acoustic panels improve sound inside a room. Stopping sound passing between rooms is a different job measured by STC (Sound Transmission Class). For bedrooms, aim for walls of about STC 50 because most bedroom complaints are about sound coming through walls, which panels alone do not stop.
| STC | What you hear through the wall |
|---|---|
| 30 | Normal speech easily understood |
| 40 | Loud speech heard but not understood |
| 45 | Loud speech barely heard |
| 50 | Loud music faint, speech inaudible |
| 60+ | Most sounds inaudible |
How to reach STC 50
- Add mass: a second layer of 5/8 in drywall. See mass law.
- Decouple the two sides: resilient channel, staggered or double studs. See decoupling.
- Fill the cavity with mineral wool insulation.
- Seal every gap with acoustic sealant, and treat outlets and doors. See flanking paths.
Compare real wall assemblies in our STC assembly guides.