I have a wet-dry canister vacuum that was way too loud.  I built a sound
deadening box for it , and now I use it without ear protectors.  About 40$
material , incl. : plywood (or other like material) , a way to cut it , foam
rubber , swivel casters (optional) , I used 4 window turn locks for the
removable top (you'll need to remove the top easily) , about 24+ ft. 1x1 in.
furring strips , wood glue , screws or nails , either staple gun or glue in
the foam rubber.  Also got an extra hose and attachment kit that allows 20
ft. radius before moving vac. (optional).  Have run it 30 plus minutes over
100 times and no overheating.  I always clean washable filter after a 30
minute marathon or doing my wood shop.  Ended up with a 17 x 19 x 21.5in.
box.  Now it's runs more quietly than my dustbuster.