I just had a Carrier 2 ton AC and Performance 80 installed in a 887 sq ft. condo.
The return grill is in my hallway closet. 26"x16". With the AC going, it's
noiser than I would like. I have a pic for some suggestions to baffle or
reduce the sound. It almost seems that cavity is huge and could well
do with some noise reduction remedy. It's like a mini hurricane in there.
What I mean by that is that there's actually downward flow too and some
of the light insulation debris can be seen moving around by the turbulence.
It that normal? The duct work is pretty good sized round.
The vents on the walls are fine, sound wise.

Anyways, some ppl are limited to their return vent area to mess with.
I'm sure not. That white texture overspray is where air enters in.
I'd appreciate some baffle suggestions. What's better than carpet to lay on the floor in there?