If you live in a condo and install an hardwood floor, people who live in the appartment underneath yours will hear all the sounds you produce, due to the concrete found under the wood floor. Soundproofing membranes prevent this phenomenon. A large variety of them exist and provide advantages when compared to one another.
FIIC is rating the acoustic insulation of a floor to impact noises. For an example, the noise made by a cauldron hiting the floor will be heard authentically in your condo. FIIC represent the sound heard by the people lodging underneath your condo. The membrane will stop or diminish the sound they will hear.