I've said this in a couple of other posts. It all depends, and it especially seems to be how many deer you have in the area, and how many hunters.
In a place where there are few deer and lots of food, a deer hears a wedding ring against the shooting rail and that's it.
In a place where there are lots of deer and a lot of food, a deer hears you coughing up a lung while talking on a cell phone and . . . so what? Deer may run away, but there are plenty of deer to fill the void.
Few deer/ sparse food? If your oak tree is the only one dropping acorns that deer may be looking up when she comes in, but she will probably come in.
Lots of other hunters? Once deer key on to fact that there are noisy humans in trees they get very wary. That article on hunting pressure in one of the latest D&DH's was right on.
I grew up in deer hunting at a time when the herds were not what they are now. Forage was ubiquitous, and deer were scarce. One bust, and that might be it for the season. Now I hunt in a time and place where the deer herd exceeds the human population in the county by a substantial margin. I can get away with a lot
If the deer are not aware that death lurks above them, it also is a lot easier. I have dropped a book out of a stand as I was getting ready to take a shot. I've dropped gloves, hats, and even a set of binos in front a deer without so much as a second glance. Then again, I've brushed my hand on my pants with a wary doe present had sent her running like she had been scalded. The weirdest ones are the deer that witness rifle shots and even muzzleloaders discharging and go back to feeding. Those I still can't fathom.