Between floors there are two ratings: STC for airborne sound such as voices and TV, and IIC (Impact Insulation Class) for footsteps and dropped objects. Building codes commonly require STC 50 and IIC 50 between dwelling units.
- Add a resilient underlayment under the floor finish above (improves IIC most).
- Hang the ceiling on resilient channel or isolation clips (improves both).
- Fill joist cavities with mineral wool.
- Add a second layer of drywall with damping compound.
Clouds and tiles do not raise STC or IIC significantly. See IIC explained.