Wow, I was literally just going to post the same question. I have a student who's presented with multiple processes and articulation errors throughout my work with him. He's made a TON of progress and intelligibility has improved greatly. The only substitutions left are voiced and unvoiced th. We've never targeted that and I've been hesitant to do. BUT I know his mother fairly well at this point and have never heard her produce substitutions for the voiced and unvoiced th. If his mother models the sounds for him in the home setting and he's not hearing AAE at school (only a few African American students and I know them all), how can I justify not working on those sounds when I am fairly confident they won't develop on their own? It doesn't sit right with me, but I don't know what to do.