This is probably the best looking sound insulation I've ever seen! Created by Swedish design studio Form Us With Love, Hexagon are a collection of hexagonal discs made from wood wool (a product made of wood slivers, usually from logs) that are environmentally-friendly, water-resistant, and moisture and sound absorbent. Check out a video of the installation you see above:
The process of making wood wool cement isn't difficult: first, wood slivers are cut from logs, then they're mixed with water and cement and put in a shaped mould to dry. (You can see the process in the 4th and 5th photos.)
See more at Form Us With Love.