After reading another post about weird sounds I've decided to post my own.
I haven't been able to find a recording that sounds anything like what I heard but it was best described as a loud husky "I'm getting ready to puke" type of sound with a trill at the end.
It took place in southern PA in early October just before sunset. It was loud enough to fill the shelter area and neither I nor my friend who grew up in a rural area hunting could figure out what it may have been. We made a guess that it was some type of bird.
It seemed to come from up in the trees as best we could tell but it only sounded once so we couldn't really pin point it.