Heavier barriers are harder for sound to shake. The mass law says that doubling the weight of a single layer raises its sound insulation by about 6 dB. That is why two layers of 5/8 in drywall beat one, and why concrete blocks so well.
- Use 5/8 in Type X drywall rather than 1/2 in.
- Add a second layer, staggering joints.
- Mass-loaded vinyl adds mass in thin form where space is tight.
- Grout-fill hollow concrete block.
Mass alone has diminishing returns. Combine it with decoupling for big gains.