Symbolism, Imagery, Allegory
Music is a big deal to Owen Armstrong, who practically lives with his ear buds attached to his head. When Annabel first meets him, this is what she notices about him—he's always listening to or talking about music. In a way music is how Owen expresses his true inner self.
So when we think about music in Just Listen, truth should never be far from our minds. Because not only is music a way that Owen expresses his true inner self, but it's a tool he uses to encourage Annabel to begin expressing herself honestly too. Owen insists that Annabel share her real opinions on music, and as she does she begins to get more in touch with her self and form an identity that is truly her own. And as she does this she also realizes that other people—like Whitney—just may have inner lives that she hasn't seen before too:
I looked from her to Whitney, who was sitting in my father's chair. Who knew she was an Ebb Tide fan, that she had imports, that she was possibly, in Owen's view anyway, enlightened? (10.73)
In the end music is one of the things that helps Annabel become more confident. She even takes over Owen's radio show for him when he's grounded, and instead of playing his playlists she decides to create her own. It seems like music has really helped our girl come into her own.