If a blind man strikes a match that no one else sees, does it make a light? Well...yes. Whether or not anyone's eyes intercept the photons that are produced, the light itself still exists.
Similarly, when the tree falls, the traveling wave (the sound) still exists regardless of whether or not it interacts with anyone's ears.
I don’t think I am quite getting it across, yes we can probably assume that if a blind man strikes a match that makes a light but the IMAGE of that lit match only exists in the mind of a viewer, it is the seer’s interpretation of the light energy.
Similiarly we may call vibrations sound but the PERCEIVED sound exists only in the mind of a listener. That is why the totally deaf person is unaware of the tree falling unless he feels the vibration through the soles of his feet or, in the case of a really huge tree, in his body, this is perceiving the vibration as vibration, hearing it is perceiving it as what we call sound. Perceived sound is not the same as vibration. I once saw Bob Guccione being interviewed on television and his voice was so low pitched that I could both hear the deep bass and at the same time feel the vibrations in my own chest. We may refer to both as sound but they are not one and the same. If I had been stone deaf I would not have heard his speech but I WOULD have felt the vibrations in my own chest.
All this may sound to some like semantics but there is more to it, it just isn’t easy to say clearly, at least not for me.