"it depends how you define sound".
The way I define it means that if a tree falls in the forest but no one was there to hear it, it still made a sound.
On another note- what about "turns"? Are they immutably individualized per person or are they a generic, ephemeral, transferable thing?
For example, if 4 of us are playing Risk or Monopoly and I decide not to take my turn, is the next person who plays taking "my" turn or is he taking his? After all, my turn wasn't taken, and I was next, so the next turn that's taken must be mine, right? Or he taking both? (No, he can't take both since he only gets one move or action, so what happened to "my" turn? Where did it go?)
Does the "turn" only instantiate and get played when the supposed "owner" takes it and uses it?
Can I actually "give up" my turn? If I do, does the next player "inherit" my turn or does my turn just disappear? Or does it wait in limbo until I finally play it?