> When an person, animal, or thing emits a noise, it sends vibrations (sound waves) through the air... [eventually,] nerves carry messages from a bunch of receptors in your ear up to your brain. Your brain then recognizes the sound, or "hears" it, and tells you what you are hearing. The thing you hear is a SOUND.

> So you see, I have to be correct, right?

> ~Den-"do you hear what I hear?"

Your reasoning is absolutely correct (or should I say "absolutely sound"?), to a point. The answer to the question "if a tree falls in a forest, or if a radio plays in a cottage, with nobody around, does it make a sound?" is immediately apparent once you define what a "sound" is. If a "sound" is "vibrations of air molecules", then of course a tree in a forest, or a radio in a cottage, makes a sound regardless of who's there -- the air molecules still vibrate, don't they? On the other hand, if you define a "sound" as "something that is heard" then of course, if nobody hears the radio or the tree falling, then there's no sound. Indeed, there is nothing deep or philosophical about this question; it is entirely semantic.

However, it is not correct to say that "the thing you hear and /only/ the thing you hear" is "sound. Often, especially in physics, people consider the vibrations in air by themselves to be "sound". This, as I have stated, is simply a matter of semantics and a measure of the imprecision of the English language. (Britannica.com defines "sound" /both/ as "the sensation perceived by the sense of hearing" as you would have it, and as "mechanical radiant energy that is transmitted by longitudinal pressure waves in a material medium (as air) and is the objective cause of hearing", as your cousin would have it.) So you see, you and your cousin are /both/ right!

Of course, there /is/ a way, sort of, to make this into a philosophical argument. "I will define sound to be defined as pressure waves in air. However, I believe that the Universe exists only in my mind and that it is not objectively 'real'. Therefore, if a tree falls in the forest but I'm not there, the tree doesn't actually fall. It just happens to /have fallen/ the next time I go there (it's not real when I'm not there). So, since the tree doesn't actually fall, it can't make a sound." This would be an argument about whether or not the universe has an objective existence, rather than a simple semantic argument -- this would put it into the category of philosophy. However, I believe that such an argument would be silly.

-SB