I agree that the fastest quietest bows can still be heard and ducked by an alert deer but the faster the arrow the less that deer will be able to react. That's just simple physics. Also another thing to think about is even with the fastest bows shooting an arrow @ idk 330-340 ish fps speed of sound travels at approx. 1,085 fps. I've heard of alert deer having reflexes or reaction of about .05 seconds.