From a directional standpoint they have 1 degree hearing as well. Acording to Rick Jamesons book on coyote calling if I remember correctly that meant that at one mile they could tell within 33 feet of where the noise came from as well. As for how far I have seen them in the bino's well out to the mile and a half mark, Blew on the call and they would turn and look right in my direction, then just go back to mouseing. The trick is you could be calling and there could be half a dozen in the area that just aren't interested, female in heat in the area, just not hungry,
figure they will check it out later, gotten wise to the rabbit call as danger not food , temperature, would rather lay in the sun like a welfare recipiant, they heard you come in to the area.