Re: is ventus the mysterious voice
The KH1 Ultimania confirmed that the voice for Sora was Mickey. I don't remember where it was stated, but Roxas in KH2 was hearing from Namine (might have also been the Ultimania)
You know, though Nomura originally had that idea in mind... I have to wonder if he might have changed it now. Technically he could alter that fact, since he never said that in an actual game. It would just make a lot more sense if it was Ven, you know? (Plus, if it came down to it, he could just say he meant Riku's "guiding voice" or Sora's in Re:Coded. LOL.)
Though, technically, we won't know for sure unless Nomura brings it up again, here are some of the reasons I think it's Ventus. For one, when Sora and Ventus are talking towards the beginning of BbS, when they both say "Open the Door", Sora's voice can be heard alongside Ven's. This could be a hint that Ven might guide Sora in the future (the way Sora once did him).
The fact that Ven's armor tries to protect Sora from the Darkness in DDD might also be a hint.
Something else I noticed is how in Sora and Ven's discussion, Sora says, "Where am I?" Ven, however, says "Who's there?" That scene is parallel to one in KH2 where Sora once again says, "Where am I?" to Roxas', "Who's there?" Maybe Nomura's hinting that Sora and Ven (and Roxas
does have Ven's heart) talk a lot by doing that? IDK.
It could mean nothing, and just be a cool parallel Nomura made. But at the same time, who really knows? But for consistency sake, I'd prefer it it Ven was the voice.
And in case you don't know which parallel lines I'm talking about, here's videos of them:
Birth by Sleep, English cutscene: 03/93/192 - A Voice Amidst the Waves - YouTube
Kingdom Hearts II, English cutscene: 12 - The Bright Sunset - HD 720p - YouTube