It's pretty loud; sitting about 6ft away from it, it sounds like someone is vacuuming in the room next door.
My machine also has a loud scrunching noise (ribbon cable inverting) on each head pass, which to my ears is more irritating than the Dyson whirr of the fan inside the machine.
If you've coexisted with a Cisco networking switch buzzing away, or a server of any kind, then it's comparable.
Hope this helps.