Well, if he had to speak. maybe like a high-pitched chirpy voice. Although, I'd rather him talk like Frenzy did in the last movie, techo gibberish with a few english words scattered so you have a general idea of what he's saying. Or maybe the sound of an RC motor whirring.
Would be hilarious if it was a deep Seth Macfarlane voice, like Brian the Dog. just toatally out of character.