Well I will tell you I have heard it and I never knew what it was until now, I have allways described it as a kinda a nasely growl with kind of a hiena wheeze to it. I was setting up my climber a few years ago and was there very early because I had to hike back there like 30 minutes then set me stand up so I knew I would be making noise, it was like 430 am and as I was quietly setting up my stand on the tree I felt really un easy and kind of blew it off as never being in the woods at dark with no light, then I heard foot steps,,,,, then I heard it circling around me. At this point I stop trying to be quiet and started trying to get in that stand! Just as I get my last foot in the sturrup and can climb the woods came alive!! I hear something crashing through the woods coming right at me at less than20 yards away and closing fast making the most horrific noise I have ever heard. It was so loudit seem deafining Iwill never forget it. Luckily I was able to get about 10 feet up(2-3 seconds)before it got to the tree. Then I heard it walking around the tree looking for me of course I didnt stop till I was at the top of the tree, lol. It eventually walked away and was long gone by day break. Well you heard the noise, I have never ever heard any thing like it and never knew what it was that made it, but that sounds alot like what I heard that morning.