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

Sounds travels best through dense materials, the less dense, the less sound. Sound travels much faster in water than air, for example. Sound also doesn’t travel well through the water/air transition. From above it’s hard to hear anything below, and vice versa.

So we take a very light foamy material full of air holes. The sound goes through the material, then through air, then material, then air, and so on. This is pretty good at deadening it.