Remember how a couple of days ago I wrote about Amy's first plosive?
She seems to have mastered it now; today she often said lovely words such as [æbæbæwæwæbæbæbæβæβæbæbæwæbæbæβæβæbæbæwæwæbæbæ]. (Judging by the length of the word, her "native language" is presumably something agglutinative. And with a fairly minimal phonology.) And Stella said she's been talking like that most of the day.
So, mostly [b] (voiced bilabial stop) but also several bilabial approximants and the odd voiced bilabial fricative. Bilabials certainly seem to be her thing. (And I think the vowel is [æ] rather than [a]. You could make a case for it being phonemically /a/, though, I guess.)
That follows the learning pattern she's already shown in a few other things: do something once, then several days later start doing it again, this time consistently.
Tomorrow, [æbæbæbæbæ] ("the world")!