When establishing your style and emotions into a musical idea, the "voice" of your personality shines through. When people say "voice" what do they mean specifically by "it means style"?
Can that style mean that this composer tends to do "this or that" in their song such as creating alot of surprising dynamics? Or similar melodies? I'm a little lost.

No one knows? ._.

It's hard to know exactly what someone else means but I'll take a shot at it. Anything we do we do in a way that is not exactly the same as anyone else, that is why handwriting experts can take a signature and verify if it is genuine. No one else can write your name exactly the same way you do no matter how hard they try to imitate you. It's the same with composing music, you may not be thinking about developing your own style but your music will none the less bear your signature in the sense that no one else would have written it exactly the same way you did. So back to the original question your voice is all of the things that make your composition different to anything that anyone else might create and can't really be nailed down to just one or two attributes. I suppose another way of looking at the voice is that the classical composers who are long dead continue to speack to us through their music, and each has a unique voice.

I think you already answered your own question. I feel the same way: to me, "voice" feels personal than "style", and is representative of your musical personality.

Borrowing Chris's signature analogy, I'd say "style" is comparable to whether your handwriting is curly, bloaty, tilted, etc... but even these stylistic descriptions are not enough to fully describe the signature, which is comparable to the "voice" (or "sound", that's another one).

A composition student may be able to imitate a particular compositional style by following a set of rules, but I wouldn't say that that's their voice unless they use it "subconsciously" at a certain level.

Over last summer, I approached a jazz teacher who basically said he didn't know how/what to teach me because I had already developed my own voice (and therefore difficult to develop another genuine jazz voice, I guess that would be like having split personalities )

Just my tuppence worth.

A set of rules? The thing is I don't know how this "personality" is defined.. But thanks for responding.

One of Schoenberg's most famous essays is on this very subject!

http://grace.evergreen.edu/~arunc/texts/music/schoenberg/schoenberg.pdf

This is exactly why I like this forum: people who already have lots of background to answer the poster's questions often do so, and others who are searching themselves offer (generally) useful "try looking in this direction" tips. Thanks, all.

Your voice and your style has to do with two things:

1. Having a coherency on most/all your output. If you work on dozens of diffent styles and genres it becomes more difficult, but if you can spot things that are recognisable as yours, then... you're on your way.
2. The second is your... fame. If you are the first to do something and people know it, they label it on your name. Ligeti sounds like him, because he did it first. Penderecki too, etc...

My "signature" or "voice", etc., might be in my choice of ornamentation, i.e., my "licks;" the way I choose to "flavor" a motif or passage.

www.frederickwarner.com