DIY acoustic panels
At the end of 2012 I moved to a flat which had a very noisy water pump downstairs. The noise was coming through the floor and especially through a wall next to my bed. I decided to try and build some heavy duty acoustic panels to dampen the noise.
I made four panels. The dampening material is 100 mm thick Paroc stone wool, as it was cheap to buy in 1170 mm * 565 mm blocks. It was also a good size for a panel - I made two with that size and two larger, sized 1735 mm * 940 mm. These would be inner frame measures. The bigger panels are made of multiple pieces of stone wool.
I bought some fabric online and decided to make it a two-layer design: first a black one and then a shiny tulle on top. I tried not to use too thick a fabric for the bottom one so as not to work as a reflector. I stapled both the fabrics on the frames. This was very tricky to get right, but I kept improving as I went on.
The end result is pretty fine. The panels do look a bit DIY, but are fine as interior decoration if you have big black loudspeakers to go with them as I do (a pair of Klipsch RF-63). The tulle fabric reflects light beautifully, yet is nondistractive.
Do the panels work? Yes, mostly. For my original purpose of attenuating noise coming through a wall they did a mediocre job. Too bad the noise coming through the floor was still too much for me, so I moved away. In my next apartment I used the panels to block the sounds of a very noisy old refrigerator next room. They did a great job and I could sleep in peace at night.
After that I've used the panels to attenuate radiator water flow noise and to dampen small room reverb so that my place doesn't sound like a bathroom. For that they do a great job, as the surface area on these panels is quite big. For just the reverb dampening purposes I would use much lighter panels, though. These are very clumsy to handle and don't really benefit from being heavy in that purpose.