Diy Sound Panels Reddit. Purchase 12x12 panels with a 2 depth curve relief. You can also layer them on top of each other if required.
A lot of people opt for more expensive solutions without trying this simple and quick fix. 7.2.6 atmos speakers might just be rsl since i can't hange these on the ceiling plus 2 gsg devastators with kraken subwoofers and 2 rythmik dual sealed subs for left and right channel with minidsp active crossovers to make the left and right full range for. He goes pretty in depth.
The concrete walls and air gap (3) will dramatically reduce any direct transmission of noise.
Spending a little bit more money will give you access to panels that work a little bit better. Towards the end of the video he compares them to much more expensive acoustic foam annnnnd, i must say, the results are pretty amazing! Plugged solar offers an innovative solution: Ideally you would get some old theater curtains (these are also fireproof to some degree unlike foam which is a fire hazard) but even thick one from ikea will do a better job than foam.