Joan: I tend to agree with Chas; however, the greatest indicator for the air moving system itself (exclusive of background sources) would be the velocity in the duct. For comfort "cooling" in inductrial applications, the maximum recommended velocity for 3,000 to 6,000 cfm high velocity systems is 3,000 fpm; which at 3,000 cfm would require a duct of 1 ft2 area.
HOWEVER: is this sufficient velocity to move the dust along?
I would think that perhaps the equipment producing the dust: sanders, planes, chippers, etc might produce more sound power than the collection system, in which case the quietest collection system wouldn't matter!