That’s probably just Ducky going through puberty, you just never figured it out yet.
Jokes aside, I’m glad I wasn’t the only one who noticed that. I mean, there are other voice actors who grew old and can still do their main character voices (Anndi McAfee, Jeff Bennett, Meghan Strange, and obviously Rob Paulsen), but I’ve always felt Aria’s voice was out of place.
I’m not saying that her voice for Ducky today is bad, is just that Universal should’ve found a voice actor that is younger and fit for Ducky, instead of keeping someone who doesn’t really fit the voice anymore.
Also I think I started hearing Ducky’s voice become slightly deeper on the 12th movie, so I believe this issue has been happening since around 2006 (or 2007).