Hendrik is hitting this stage that I think is technically called Explosion of Cuteness. He is so interested in the world around him, and he's beginning to use more words. Just the other day I got out his ball and asked him to say "ball" and he replied with "ga!" But the rest of that day and ever since he has consistently called his ball ga. Cool!
Part of the Cuteness Explosion is that he is using more vowels. Whereas before he could only really do the a ones (like in dada and dog dog), but now he can do ai (hi!) and o (he has this cute surprised "oh!" sound that he uses whenever something amazes him, which is about once every five minutes). You can hear it in this video, and at the end you can see that he gets tired of talking to me and wants to see what Shelby, our dog dog, is up to.