The case
A tree falls where no one is present to hear it. Pressure waves propagate. No ear, instrument or record receives them.
Held fixed: the event happens. Varied in the puzzle: whether anything perceives it.
What it can show
That “sound” names two things, a physical event and a perceived one, and the puzzle dissolves once they are told apart. For the pragmatic-transport line it is the baseline with no sender: nothing in the fall was produced for a receiver, so it has no intended meaning to fix and no fidelity to measure. It is stipulated, a thought experiment, and shows a distinction, not a fact.
The owner’s storage variant (CASE-043) adds a sender and a projected receiver, and takes away only the actual one.