Timber!

What a wonderful twist on an ancient philosophical question. But i have to say 'unspecific' nailed it.

The fact that the person is deaf and sees the tree fall answers the question. Impressive, since it took us thousands of years to answer the original.

Even in the original, being "witness to the vibrations" solves our conundrum.

When a tree falls, it never makes sound. That's what ears do. The tree merely makes sound waves. An ear is tasked with turning those waves into sound. If there is no ear, there is no sound being made.

But now i'm extremely interested in another question raised by our discourse: If a tree falls and no one sees it, who cares! :)