Character voice also affects word choice, rhythm, and pacing. But in character voice those things are influenced by the character's background, gender, history, age, education, regional location, time period, etc.
Okay, maybe this will help, because it definitely helped me. I attended a workshop once where the author explained author voice by saying that you could pick up any one of her books no matter what the subject/character/plot and know that she wrote it.
Finding Character Voice