Falling trees making sound paradox

We have the hoary old "paradox" of whether a tree falling in the forest where there is no one around makes a sound.

I had this explained to me once by an old philosopher that this is not a paradox at all but just a confusion of two distinct meanings of the word "sound." Is it vibrations in the air? In that case the falling tree makes a sound only if there is air. 

Is it such vibrations striking the ear drum of a sentient being and ending up as the sensation sound in a mind, in that case it is possible the tree makes no sound if there are no sentient beings around.

So the seeming paradox is not a paradox but just a case of asking two different questions which are entitled to have different answers.