Using a decibel meter app on my phone (for what it’s worth) my Quincy qt54 is 85db. On the same day I tested my little 27 gallon 5 hp annoyingly loud Coleman was also 85-87 db.
The Quincy two stage pump is so much easier on the ears though. Initial startup surge is loud but once it is running isn’t too bad. I can be in my garage with it where i couldn’t with the Coleman.
Wear ear protection and it’s not an issue regardless.
I went out in front of my neighbors homes and didn’t seem too much noise.