Oh I think they notice it, and do react. But if you keep the shots less then 20yrds and shoot none spooked game it does not matter.
This is my first trad year, and I use stuff that I have made myself. I shot at 3 deer and it the arrow was not the reason I missed. The first 2, I just shot over them. I connected on the 3rd.
Both misses did not spook the deer that bad in fact. The first ran off about 25yrds and calmed down and walked off. The second ran out about the same, and I grunted her back in. I did not shoot at her for a buck came in I was able to take.
Just what I have seen thus far.