I don't think the cloak should be as audible when standing still. I'd like it to be silent but i realize that's asking for too much. Maybe have level increments decrease the volume of it? While standing still that is.
Sorry Telos, but I don't think that's a good idea. I've seen or rather heard a lot of Assassins camping next to the other team's span room (3 in one match...) and when they do I'd like some kind of warning so I can hunt them down!
Standing still with level 3 cloak is a deadly place for an Assassin to be. Not only does she recovery her cloak when she fires her Shuriken Launcher it's one second of guaranteed criticals. Making her not hum while standing still will make her too dangerous, imo.