What is the difference between a "sound" and "noise"? The main philosophical riddle is, does something exist if it is not perceived? Would the tree even exist if no one is there to see it? Common sense says that of course the unobserved world exists, but this isn't about common sense, it's about metaphysics.
Sound has many meanings as I presented and so did bubblehead. I used meanings that would still fit the context of your sentence.
Noise and Sound are both physics terms that are acceptable for the question posed and the context of the sentence. I throw out noise as it is the more classical physics term used around the time of that question's popularity in the mid-late 1800's.
To ask if the tree even exists if no one is there to see it is just drunken "waxing philosophical", a parlor trick of conversation if you will, as in the context of the sentence, the use of a stating a tree falling infers that the tree exists. In any language, context is king for the definition of the any word used in that sentence....no matter how much people would like it to be different.
And yes I know the history of that question, and really while interesting, it is very flawed as it expects people to take the question out of context and infer, which is what makes it a parlor trick of language. In other words, to infer anything different than the sentence presented is would mean the sentence needs more qualification and less assumption. (i.e., to ask if the tree exists would further qualification to help infer such).
