Your comment regarding your client is very similar to many
experiences that I have had in working with adolescents. It seems to
me that these people have had no practice, or experrience or "model"
(whatever label seems to fit) with emotional expression, and have
found that music provides them with a comfortable outlet.
Have you tried to talk to this client about some of the underlying
philosphy that she identifies with when she sings some particular
song? I've found that investigating this type of meaning making with
the client allows them to own some of their experience more openly.
AJ