A sound I have never heard before, was when me and my older brother were walking in the woods to get home and him and I both heard a humming noise that turned into a growl, but not like a dog growl we knew this because we both have had a dog growl at us plenty of times this noise startled us as we were walking. It came from behind which is a major reason it startled us and caught us off guard and stopped us dead in our tracks normally when you hear this sound you run we could not run it was extremely odd, because this was about our third or fourth time walking through these woods and never heard it any other time. Frozen in fear we slowly turned around to look behind us we did not see a thing, but the growling was still there after we got the feeling back in our body we picked up our bags it was getting late so I checked my phone to see what the time was it was 7:30 p.m. we walked a little further into the darkness the light slowly went away