[Mijotter]

Soundproofing Air Return Plenum. I have 2 air return plenums in my basement and they echo and vibrate something aweful. What can i do to sound proof them or at least stop the echo/vibration. I'll be decoupling the ceiling so that'll help but still. Also, they're nailed flush to the joists but is it ok to seal them to the joists as well so there's no leaks whatsoever.
Thank you.

 

[gregzoll]

Some use sound mat that is used in cars for dampening noise.

 

[beenthere]

Looks like panning. If it is, you might want to remove it, and then replace it with thermopan.

 

[Mijotter]

Thanks guys for the input. beenthere I looked at your idea of the thermopan and it's perfect. and a lot more cost effective. Going to replace both plenums with it and thankfully my local Menards has the pans in stock