You would be surprised how much noise there is coming off an arrow. I don't think it matters too much in most conditions. Real close is probably when it's the worst.
I was sitting on the ground in texas when an educated buck came out of the brush. He looked hard both ways and then stepped out on the golden Highway(corned rd). It was obvious that he went on high alert the moment he stepped on the rd. This was about a 140" buck and he came within 5 yards. I couldn't understand how he couldn't hear my heart pounding, or my arrow rattling off the side of my sight window, but when I drew my arrow back (only about 15"s) he jumped out of his skin. Within a couple of minutes, he came right back through on the same path and this time I was only able to draw back about 10"s before he jumped. I watched this buck leave out slowly a different direction, and never once blowing or looking back where I was.
It was without a doubt, most definately the noise of the arrow sliding on the rest (bear hair). Now when I got back to camp, there were many suggestions on how to correct the problem including a gift of some mole skin.
I steel wooled the shafts slightly, waxed them a little, changed out to calf hair, mole skin, beaver tail and I felt that there was little improvement. The wax probably helped the most.
The best solution was to hunt less educated deer.
Bigjim