@OmSigDAVID,
It's not about the tone of voice as such. When you claim self-defense, it matters whether or not you provoked the trouble you're defending yourself against. Tone of voice, and any fighting Mr Dunn uttered, would have been evidence about his intentions.
That said, I was so absorbed with my imaginary videotape that I forgot there were witnesses. In particular, when your own girlfriend testifies under oath you were
not in danger when you shot, that's pretty good evidence that you weren't.