Answer: mainly mineral wool and natural wool.
The insulation mainly used for soundproofing a floor is mineral and natural wool. Both materials are effective if you choose dense panels. For example cellulose panels at 70 kg / m3, wood wool panels at 55 kg / m3 or even wood fiber or cork will be very effective and will ensure good sound insulation of your floor. Mineral wools have proven themselves in recent years. This insulation must be sandwiched by the masses of the floor, in general a plasterboard or a gypsum or cellulose plate. You too, send us your brico question