"If a tree falls in a forest and no one is around to hear it, does it make a sound?"
If a tree falls in a forest and no one is around to hear it, does it obviously make a sound?
If a tree falls in a forest and the police wasn't around, does it make a sound?
If a tree falls in a forest and the police is investigating, but the prosecutor decides not to press charges (for insufficient evidence of violating the forest noise ordinance, for instance - the officer did not have a calibrated decibel meter with him at the time), does it make a sound?
If eight trees fall in a forest and someone was around to hear it, do other falling trees in the forest make a sound?
If trees in a a forest in a land, far, far away, fall and plenty were around to hear it and record it, do falling trees on the other side of the land far, far away make a sound? Or our trees are perhaps different species of trees?
Sound, like color is a perceptional property of (in this context, let's stick with) humans.
If a tree falls in the forest, it does
produces vibrations that travel through the air. If no one is around to hear it, it doesn't make a sound.
If the tree produces vibrations that travel through the air that are outside human perception, it doesn't produce a sound.
If the sun emits UV light but we can't see it, is it visible? To us, no. None the less, there are the electromagnet wavelengths of UV light emitting from the sun!
What is and what isn't human perception should be the first question defined and specified. https://en.wikipedia.org/wiki/Psychoacoustics
Hearing is not a purely mechanical phenomenon of wave propagation, but is also a sensory and perceptual
event; in other words, when a person hears something, that something arrives at the ear as a mechanical sound wave traveling through the air, but within the ear it is transformed into neural action potentials.