so if a tree falls in a forest and no one hears it?

No one knows...

It does make a sound. It makes a sound of a falling tree.

Sound is simply air vibrations caused by something moving that air. Since we can assume that the tree did not go from standing to having fallen without moving...we can also assume that it made a sound when it did so.

Science believes that the tree "heard by no one" makes a sound when it falls - through careful observation of other trees falling when we are around to record the sound or hear it or detect it by other means.

Science also isn't here to prove whether some deity or other was watching the big bang or not. Until said deity makes itself known, and provable, and can prove that it was present at said big bang, there's minimal point for a scientist to deal with that subject matter.

That being said, there was no AIR during the big bang, thus while it generated a huge amount of energy, you couldn't have heard it!

Depends how you define sound. If you are talking about the actual vibrations caused in the air which hit the ear drum allowing you to hear it, then it still makes a sound. If for something to be a "sound" it has to vibrate the eardrum, then no it's not a sound. Also, sound doesn't travel through a vacuum, so I don't think there would have been much to hear from the big bang. If there was nothing, not even a vacuum, prior to the big bang, then how would the sound waves have traveled?

@silverlynx Well said! Shame I couldn't phrase what I said in a way that's more understandable, like yours.

Science doesn't say that it does not make a sound. Science says that we cannot prove that it made a sound, but that based on the laws of physics and energy conservation, we have extremely good reason to believe that some of the energy released was transferred into sonic waves. As for the God issue, the "band" in that phrase doesn't really refer to an auditory phenomenon, but rather acts as a metaphor. But yah, sure. If God existed, I'm sure that he would have heard the big bang.

Technically, someone has to hear it, like an animal. It would make no sense if a tree fell and it didn't make a sound for anyone/anything to hear it.

I does make a sound. It's not being herd by anyone though as it is a forest and noone is around. If I scream as loud as I can and fire of a few rounds of shotgun up in my apartment can u here it in where ever you are. Unless we are living near by, the sound is still there.