It's certainly worth thinking about. What is voice? What is it in our writing? Well, what is voice in speech? Voice is the sound of our speaking, as opposed to the mere sense. A voice can be light or dark, high-pitched or deep. It can have "fry", something which there was a great deal of commentary about not long ago.
Two people can speak the exact same words in the exact same situation and one can sound like they mean at, the other not so much. You can sound sincere, that is, or insincere. You can sound like you are lying or telling the truth. You can sound like you like what you're saying or you don't. It's the sound of your voice we're talking about here, of course. "There was something in his voice that worried me" we sometimes say. Here we usually mean something quite situational, not something durable about the person.
But we can also talk about somebody's voice in general. And this is where "finding" your voice comes in. I'm something of a mystic, or perhaps just a moralist, about this. I really do believe that your authentic voice, whether in speech or writing, is the way your words sound when you are speaking your mind, i.e., telling the truth. This is why I emphasize that when you do your academic writing you should remember that knowledge is justified, true belief. You should train yourself to write down the things you believe, not just things that are conveniently true.
In my answer to Randall, I said that I'm not sure that voice is essential in academic writing. I'm not sure that I would encourage people to "find their voice" in order to write their journal articles. Or maybe I just mean they should do it a very specialized way. In any case, rereading these loose remarks, I can see I'll have to think about this some more.