formal "T"
Zion's language is vastly more conventional than it was when he was two—as you'd expect! Except when he's using his cutesy baby voice (which isn't more than half the time) his speech pretty much follows the normal patterns of American English (since we're in Boston he doesn't lose points for dropping his Rs). As he adapts to conventional language, it's interesting to notice examples of hypercorrection he makes—most notably his use of /t/ to replace /d/ when he wants to sound official. "Here comes Spiterman!", as he pronounced very distinctly in his announcer voice this morning.
It makes perfect sense as a replacement. Clearly, he's noticed that our dialect effectively has a /d/ /t/ merger in many cases: in an intervocalic position the two sound exactly the same. He knows when we say "butter" it sounds like there's a D in the middle of the word, but also that it's really a T: a T that one might pronounce when one was being particularly formal. His "Spiterman" T replaces an identical sound—one that just happens to be spelled with a D.
If I were to draw a larger point from his little mix-up, its that we sometimes give kids too little credit: we point out all the things they do "wrong" without very often noticing why they're making a particular mistake—or realizing the tremendous amount of processing and development they're doing in order to come up with a way to systematize the craziness around them.
But never mind that, the real point is that Zion is awesome and I wish I could record everything he says to enjoy later. The things he says when he's not whining, that is.