Your ceiling must be completely exposed to soundproof it. Remove any drywall and place it aside, intact, as you will be replacing it. Only the wood struts of the ceiling should be visible.
Pack the foam insulation into the exposed spaces between the ceiling struts.
Check your ceiling carefully for holes. Even the slightest hole can let sound through. Use acoustical caulk to fill any holes.
Place a dense layer of foam ceiling tiles over your ceiling. The thicker they are, the more difficult it will be for sound to get through them.
Go back over the ceiling to check for holes. Use caulk to seal any holes left when the foam ceiling tiles were added. It is very important that all holes are sealed, so double check the ceiling before moving to the next step.
Replace the drywall you removed in Step 1. Use isolation clips to create a small gap between the drywall and the ceiling. The gap will prevent noise caused by vibrations.