Also, non-verbal doesn't mean non-communicative. They just don't use any (or many) words. But they'll let you know what they're thinking. Educate yourself on music therapy techniques. There are a lot of good videos for you on YouTube. (That's actually my next professional goal: to become a certified music therapist.)
These kiddos have a lot of life and joy to share, and music touches them in ways most other mediums can't. Enjoy your time with them. They'll surprise you.
The mom of an Au-Some kiddo.