any little noise will work, the thing you want to remember is that if you put the deer on red alert it is more likely the deer can jump the string (not that it happens all the time) but a whitetail deers reaction time is a lot faster than the speed of sound and it doesn't matter if you have a bowtech blacknight 2 that has an ibo of like 342 to 350fps the deer can react way before your arrow will hit it