To many people, the answer to this question is self-evident. Yet the dichotomous nature of such a question purely reflects one's personal beliefs. But indeed, I believe I know the answer! Of course it makes a sound. It is likely that the entire universe was created by sound vibrations, or oscilation. Yet we were not "here", in physical form anyway, to perceive this sound. Whether you believe God, Creator, Source, Big Bang, etc. created this sound it will nonetheless lead you to the same result. But if we conclude that human perception of sound is the only one that counts, we are precluding, or denying, the same life force that created us to begin with. Sound and vibrations affect everything around us, and I don't feel anyone can sensibly dispute this fact. Even in the "stillness" there is vibration, matter perpetually changing forms again and again. Thus these changes occur whether we "hear" them or not, therefore there is in fact a resulting sound from the tree that topples over. Moreover, a rock can hear sound in the middle of the forest. We may deny this fact because we reason that the rock has no intellectual capacity to hear and judge things as we do, but still, the vibration which occurs (eg, erosion) does affect the nature of all the tiny, sub-atomic particles and the energy which makes up those particles still. In our Universe all things are made up of energy, it's presence is ubiquitous whether we sense it or not.