If you've ever had the experience spending a period of time in the wilderness of your choice, you may remember the sounds that were eerily engulfed by silence.  There is a steady background sound of water running far away, the wind in the pines, the chatter of squirrels and the calls of various birds.  You may hear a curious "crack" and "snap" of an animal moving somewhere.  Hearing a gunshot reverberate around the hills and valley in an area seemingly devoid of any other people certainly grabs your attention.  In the days of the fur trade  traveling deep in unknown land, you prepared yourself for anything.