If a tree falls in the forest, and no one is around, does it still make a sound?

Depends what you mean by "a sound".

If that is a physical event, a wave that travels through the air, then yes.

If you mean a mental event of hearing, do you mean that process of hearing which requires ears and a brain? Then: No.

But if you mean simply a mental event like that one we call hearing a tree fall, which does't obviously require a brain or ears (etc.), then it may be that God, or disembodied spirits hear the crash.

So in this case: Maybe.