Cork (material)
Since cork has suberin in its cell walls, this makes the cells consist of sealed elements. And having sealed elements make it greater for acoustic insulation and even thermal insulation. Sealed elements are capable of trapping and absorbing sound. In short, suberin is mostly responsible for noise reduction! Also, lignin is another constituent of cork. It makes up about 22% of cork. One study says that it’s also associated with soundproofing and thermal insulation!