Amazingly quiet shop vacuum!

Quiet shop vacuums exist and they are much quieter than traditional shop vacs. This one was literally orders of magnitude quieter than what we were using. We bought a DeWalt Stealthsonic for our noise research. It was 20+ decibels quieter than the standard shop vacuum we were using. Here is the model we bought: DeWalt 9-Gallon Stealthsonic.

It is advertised as 50% quieter. However, 20 decibels represents 75% quieter (in terms of how it "sounds"), but in terms of acoustical energy, it is 1/100 as much sound energy (99% reduction).

This same model was also used by drywall contractors in our main office and it was quiet enough to not disrupt phone calls in adjacent offices.

Here is a comparison between this vacuum and the one our lab was using.