Sealing gaps and cracks around electrical wiring, water pipes and ductwork using acoustical caulk or spray foam will significantly reduce unwanted noise as a preliminary step for ceiling soundproofing. Acoustical caulk should be used along the perimeter of the wall and around all fixtures and duct registers to further seal the treatment. Mineral wool insulation is most commonly used in soundproofing for its density and low cost in comparison to other soundproofing materials. Spray foam insulation should only be used to fill gaps and cracks or as a 1-2 inch layer before installing mineral wool. Cured spray foam and other closed-cell foam can be a sound conductor. Spray foam is not porous enough to absorb sound, it's also not dense enough to stop sound. Avoid recessed lights or any fixtures requiring large holes in the ceiling. One small hole can compromise the efficiency of the entire treatment.
An effective method to reduce impact noise is the resilient isolation channel. The channels decouple the drywall from the joists, reducing the transfer of vibration.