Hollow-core slabs act like acoustic drums, bouncing sound waves directly between rooms instead of absorbing them. If your primary goal is soundproofing, upgrading to solid-core composite or solid wood Interior Doors will make an immediate and dramatic difference in acoustic isolation. The heavy density of the core material dampens sound transmission significantly. For the best sound-blocking results, make sure to pair your new solid slabs with acoustic perimeter gaskets or drop seals at the bottom threshold to eliminate gaps where noise leaks through.