Philosophical Thoughts

The other day I heard someone bring about that "If a tree falls in a forest and no one is around to hear it, does it make a sound?" idea and it got me thinking. The dictionary defines sound as, "Vibrations that travel through the air or another medium and can be heard when they reach a person's or animal's ear." and when you think about it, if there is no person or animal around (which is probably impossible, but in these instances we will assume that there is no person or animal around) there is no sound. Its the fact that there is no one around to hear it because so the vibrations go nowhere. Crazy, right? I started thinking more about ideas like this and came up with a similar idea: if you're in a completely pitch black room (can't see your hand in front of your face) and there's furniture or something in it (you can't see it) is it there? I could argue no, due to the fact that for you to truly know that something is there (without walking around) is to see it (which according to Descartes, is debatable). If you can't see it, then who is to say you aren't imagining it. The senses deceive according to Descartes and on that notion you will never know if that tree in the forest made the noise or if there is anything in that dark room. These are my deep philosophical thoughts right now. Any comments?