Sure, why not? Frank wants to explore a bit beyond wearing baby clothes and asked here. And the answer is that it's fine if you want to. It is, perhaps, not terribly authentic, but if it's fun and makes you amused to say it, then go right ahead.
Ajaco, remember that just because someone might be less articulate we might like doesn't mean they don't deserve a serious answer. Maybe tomorrow we'll see someone make a thread where they explain how they're embarrassed and fighting with themselves when they try to regress and ask for advice or simply affirmation that it's okay to let their inhibitions go in a safe, private place. it's the same question as this thread, if they do, or at least quite similar.
I say what ever makes you happy...if that comes naturally, but not if you're forcing it. I've never actually heard a baby say those words, but that doesn't mean they're not ok... I think, you know, when your in the zone, be natural...don't think about...oh...what is it that babies say? Hahaha...if it makes you feel awesome and cute then better go for it
Even I quietly babble in simple "baby talk" when alone in my bedroom an "regressed" into "Baby Mode". Softly whispering "Baby Talk" is very calming and comforting to me. Babies do not say words, they either cry, gurgle, sigh of prattle in monosyllable "Baby Talk".
It's okay to do exactly what feels right for you, provided it doesn't harm anyone else - and there's few things less harmful than saying "goo goo gaa gaa" and wearing plastic pants! Seriously, ageplay is all about doing what makes you feel happiest and most content. Whether or not it's 'accurate' or similar to someone else's ageplay is entirely immaterial.
But personaly I prefer make song close to the world I want to say, If someone ask me to say "hello" I will say "lo", If I want to show my diaper is wet I will say "ee" (close to pee) and I will show my diaper, you know what I mean ?