Eli5 Why is the soundproofing that is used foam-like materials instead of dense materials?

Question

Eli5 Why is the soundproofing that is used foam-like materials instead of dense materials?

In: Other

Answer 1

Sound can travel through solid objects it even in some cases is a lot easier, what sound finds difficult is travelling from one medium to another and back again, so going from solid to air to solid again and again muffles the sound.