Jim Carroll, I get what you're saying about copying what we hear. It's a normal part of the process as a child finds his/her own voice.

I've noticed that my niece (who recently started 9th grade) has her own voice when she improvises karaoke of songs she doesn't really know well, and a copycat voice when doing stuff she's heard over and over. Also she's different when she believes no one is listening. Better IMO.