When I was a child I read a book which was very influential in my life. "Where the Red Fern Grows". One thing that struck me as unusual when I read it, was the "wooping". The boy would woop at his dogs, his father would woop at his son. I never heard the term used before, and just figured it meant to hoot and holler. I was familiar with that term.
Many years later when I was visiting my future mother in law, I was introduced to her version of the woop. "Beuuu Beuuu", was how she called out to the dog in a very audible tone. I was also informed that this was how she use to call out to her children. It was very effective, her voice carried.
As Leslie and I started skiing together more, we developed our own form of communication while skiing in the trees. While skiing in the trees it is very easy to become separated from your ski partner. Line of sight might possibly extend 20-30 feet within the glades. However ear shot can extend well over 100 feet. WOOP WOOP. It works similar to sonar. Except that you do not listen for your own voice to bounce back, but your partners. As soon as you hear a WOOP you answer back with your own WOOP. Though it sounds simple and intuitive, it is very effective yet not instinctive to answer a call in the woods. A vector of information, one WOOP can tell you what direction and how far your ski partner is from you.
My regular ski partners and I have perfected this form of tree skiing communication, that we can enter a tree run, ski hundreds of vertical feet down, and without seeing each other once, pop out of the trees within relative proximity to each other. Over time each person develops his/her own distinctive woop.
So the next time you leave the mother ship without your communicator just remember Little Ann and Big Dan; WOOP WOOP!