acquiring sound

We had an early intervention assessment last week because the little dude is proving slow to talk. He's fine, though, really, and none of us have any hard worries [about that, anyway]. It's only been a week since he was pronounced borderline delayed, and already since then he's been trying his little darndest to figure out how to make his first (almost only) word--'cat'--have more of a rounded 'caaa' sound at the start instead of the 'taaa' it previously was. Man, he tries. And he's just started to fling these slightly husky 'mama's around, too. He'll point at me, smugly: 'mama.' I point back.