"My own feeling is that voice is a natural attribute. You no more control it than you can control the color of your eyes - nor would you want to... To set your voice free, set your words free. Set your characters free. Most important, set your heart free. It is from the unknowable shadows of your subconscious that your stories will find their drive and from which they will draw their meaning. No one can loan you that or teach you that. Your voice is your self in the story." - Donald Maass
Had to post this paragraph. Please, someone let me know if by doing so I am infringing on any rights. However, I wanted to share this since it is probably the best explanation of "voice" that I have read/heard so far.