People often encourage you to speak in your natural voice when you write, but do they ever encourage you to speak in your character's voice? Just saying, if someone heard one of your characters speak, without being told who was speaking, would they be able to distinguish it as that character?
If one could hear a character's voice I'm quite sure they would know which character it was, since everyone's voice sounds different. It's because one can't hear the character's voice that writers need to include clues - the obvious "said X", a particular word or phrase the character uses, etc. So I guess I'm not sure what you're asking.
I'm not really sure what you're asking, either. By voice, do you mean style, rhythm, word choice, and so on? Or are you referring to actual sound, complete with timbre and accent and all the rest of it?
Voice is much more than the physical tones produced by the larynx, and if you're doing your characters well, you'll definitely reduce the need for attributions in your dialogue. Voice is tone and rhythm and verbiage and attitude, and we each have our own voice which is largely separate from the physical expression of the words. It's true that that latter plays a role, but even in internal monologue, we sound like ourselves to ourselves.
It's difficult to give every character a truly unique voice without going overboard: Devising a six-way dialogue with no indicators as to who is saying what would require some very creative engineering to make each character identifiable by the way they speak. Having said that, it's handy to have in your mind a way that your character speaks and conducts themselves. Taking on that persona yourself can allow you to generate more fluid actions and reactions and helps avoid the common pitfall of having every character talk and think like you.
since there are many characters with dialog in a piece of fiction, i can't see it being practical for the writer to take on that persona other than when writing each one's dialog... if that's what's meant, it's what seasoned fiction writers do, to some extent... if you mean in real life, tcol, aside from when writing, then my doubt about practicality stands...
