"I took voice lessons when I was a kid and I used to sing at convalescent hospitals and children's hospitals," Armstrong said. "I think it really kind of ingrained a sense of melody in my brain at a really young age."
Armstrong said he sang songs by Irving Berlin, George M. Cohan and other writers of the Golden Age of musical theatre.
"It's stuff that, getting into punk rock, I kind of kept in my past," he said. "And then it kind of all came out with American Idiot."
Playbill got American Idiot director and co-librettist Michael Mayer together with Armstrong for a one-on-one chat for the April issue of the magazine. Find the feature here, with added audio clips in which Armstrong talks more about his past brush with traditional show music.