My own tests of every cut and every length I could get my hands on at the time showed that 2" Rayars were the quietest in flight.
Banana's came a close second.
All fletched helical where louder than if fletched either straight or with a slight off set.
If a person can hear an arrow in coming,then a deer with much better hearing plus the ability to pin point sound is certainly going to hear it coming,,,is that important ??.
To me it is,but I guess it depends on weather you just missed due to an animal not being there when your arrow arrived I guess.