Got my first double yesterday. This doe and button buck came in with a small 6 pt. Shot the doe at 140 yards and the button hung around (thought it was a doe) and made quick work with him. Got it done with my Tikka .243 T3X Lite.
I remember a podcast on deer hearing. It concluded deer hear at different decibels. They don't hear our voices well but can hear sticks breaking and metal on metal at significant distances.