The present study examines an opening scene of Joss Whedon’s 2015 film Avengers: Age of Ultron, in which Bruce Banner, with headphones on, privately listens to “Casta diva,” an aria from Bellini’s opera Norma (1831). This paper argues that the aria is a sonic representation of Banner’s inner self (Innerlichkeit), which resounds through not only Age of Ultron but the entire MCU (Marvel Cinematic Universe) franchise. I first show the ways in which Banner is identified with Norma, the high priestess of the druids, with whom he shares moral dilemmas of war. I then revisit debates concerning masculinity of Banner/Hulk and illustrate various ways in which his gender is constructed anew through music in the film. It will be argued that Banner—white, male, middle-class, and musical—epitomizes new American masculinity frequently found in post-9/11 superhero films. The paper concludes by suggesting that the notion of listening to one’s inner self through music is a specifically Romantic one, of which Whedon makes deliberate use to counter hypermasculinity and introduce a new hero: the “musical” Hulk. (175 words)