while i dont own a vortex i have seen them in action in an 'associates' grow
those bitches are loud as fuck. i hate hearing 747 in my house dude!
im big on air flow and even bigger on quiet flow.
the way you mount your fans with grommets, bungee cords, etc etc all help silence it.
insulated duct work also almost kills the air whoosing noise....
however none of that matters, imho, if you have a loud ass fan....
which brings me to the casing that the fan comes in.
imho...all fans that are in polymer plastic type casings are hella more superior than regular fans....
Sunleaves Windtunnels, Solar & Paleau TD series, and Elicient fans all have plastic polymer type casing and they are sealed... they are hella much quieter with no sacrifice to air flow....