Answer

There are several. The ceilings in most newer construction cinemas are acoustical tile suspended some distance below the building’s infrastructure. Low frequencies can easily penetrate the space between the roof and the ceiling tiles, which can reflect and re-enter the listening area sometime later, causing random cancellations at some frequencies. A thick layer of fiberglass insulation (6 inches is recommended) can minimize this problem. It also provides the side benefit of reducing heat or air conditioning loss into the plenum space above the tile, which saves energy costs. Finally, the insulation will minimize any rattling noise from light fixtures or HVAC metalwork in the ceiling.