When discussing the sound differential between rotary and vibratory pumps, we're often asked which one is more quiet; our answer is invariably: Does it matter? Your coffee grinder's the loudest thing in the room! But how loud is it? We devised a practical test to basically show the difference between the grinders, decibel-wise. What did we learn? The tone's the thing! While the decibel levels are actually quite similar, there were models that 'sounded' louder than others, simply because of a difference in tone. So the moral is ... they're all loud. :) Watch Gail's test in action!