Charlie is learning about his upper register. Also about palatal-and-back fricatives. So instead of a baby who says "geh" or "owa" or "EH" we have a baby who sounds like shrieking metal in an extrusion press or Donald Sutherland alerting his fellow pods to the last original human or some second-rate demon possessing an ingenue. And he smiles while he does it.
Long ago I read about artificial-intelligence researchers who were trying to make self-organizing systems that taught themselves how to speak. One of the things they did to simplify their job was to eliminate from consideration the majority of sounds that their machines could make, on the grounds that those noises belonged to no possible human language and hence would never be uttered. Let me just say we got your utterances right here.
I think next week I'm going to teach him how to project.