Hey guys,
we use the Durra panels as ou first layer, due to the density of the product. Awesome oise insulation and 100% eco friendly. It's just compressed straw. The panels are 50mm thick and solid. In fact they are s solid you don't need a frame if under 2700mm high.
For added acoustic control we the install Gyprock EC08 impact board. Similar to the fyrecheck board, but better acoustics, and approved by GECA. Both of these products ae also listed on the ecosupplier website.
We use the same system for our recordng studios, except we build a double layered wall.
At the end of service life the Durra panels can be chopped up and used for mulch