Yeah, but Elfangor definitely spent plenty of time as a human. It stands to reason that he would be thoroughly fascinated by having a mouth, just as Ax was (they're both Andalites, and naturally don't have mouths). Elfangor spent several years as a human, though, instead of just 2 hours at a time every once in a while like Ax, so while Ax was still playing with words years after first morphing human, I think Elfangor should definitely have gotten used to the concept of speaking sonically rather than telepathically. I was just wondering how long that would have taken him.