Re: Is Ash ageing? -
He is, but only very slowly. There has only been proof of one year passing, and that was midway through Johto. Apart from that, there hasn't been much mentioned about age. I really don't think he is anywhere near 14 though. He's at least 11, maybe 12.
As for the new voice actors, I haven't heard them, but I doubt they'd modify his voice to show he's going through puberty or anything. I'd say his voice changed a bit because they were still messing around with the new voice actors for a while to see what sounded best. If Veronica Taylor was still his VA I doubt they'd have told her to change Ash's voice at all to show he's getting older.