Reinforced concrete floor work better in preventing transmission of airborne sound compare to low mass timber floor. That is why reinforced concrete floor can be effectively used to separate residents.
Moreover , lightweight insulating material or dense material can be used for filling the spaces between timber joists to enhance sound resistance of timber floors.
It is worth mentioning that using reinforced concrete floor with reasonable increase in cost will be more effective compare to timber floors which requires extra cost to reduce sound transmission by filling spaces between joists.
However , if the floor of existing buildings is timber then , filling joists of the timber with lightweight or dense material is the only solution to enhance sound insulation.
Impact sounds can be decline considerably and effectively by applying floor covering , for example , carpet or a resilient sheet under the surface of the floor. The resilient layer will diminish the sound of footstep in either a reinforced concrete floor or a timber floor.
Furthermore , the sound mitigation used for the timber and reinforced concrete floors do not tackle airborne sound which will be reflected and might amplify to a level that is not tolerable. The sound absorption of ceiling could be improved by choosing an absorbent acoustic tile or panel finishes.