I'm not saying that there is something and I'm not saying that there isn't anything in the woods but.. There is a lot of natural noise in woods. I'm an ex-hunter and camper. I used to spend a lot of time in the woods. I'd bet there are a lot of natural explanations for a majority of sounds. Tree branches do break and fall from trees naturally. It can sound like someone walking in the woods. Especially in fall when the leaves are crunchy. A couple of chipmonks scared me because of the noise they made. They were trying to scare me off because I was in their "place". I moved 10 feet away and they stopped. A squirrel going through dead leaves can sound like an army.
Wind blowing through trees can sound like moaning and groaning. Just because there is no wind at ground level doesn't mean there is no wind 50 feet up. Also, look up in the trees for different animals that could be making noise. We are used to looking on the ground or at ground level for things. Animals can blend in with their surroundings. Especially deer. When in a cautious mode, deer will move several steps and freeze. You may not notice the deer but you'll hear them move.
People like to abandon their pet dogs. Some times the dogs get hit by cars or get attacked by other animals. Their moaning from pain, etc can carry a distance. Then there are coyotes and other feral animals that create howling and grunts.
When you hear something, keep an open mind and try and document the sound. Carry a notebook, pen/pencil and watch. Write down what you heard, when, where, weather conditions and what you were doing at the time. Try to describe the sound in writing. If you can, bring a digital recorder with you to record all the sounds. See if it forms a pattern. Don't automatically assume every noise you hear in the woods is paranormal. Even if it is B.G. Also, bring a camera. You never know if you'll get the million dollar picture.