That was not the reaction that Steve expected from his humming. At least Bruce can't change into the Hulk here since he isn't sure what kind of nightmares his friend might be having lately. But it wasn't something that Steve really would be afraid of even if Bruce could change. He wouldn't hurt Steve but he might need someone to talk him out of tearing apart the baths.

"Sorry. I didn't mean to wake you." The question about the humming caused Steve to pause and think threw which songs he'd gone through. "Some Andrews Sisters. Some instrumental stuff that Natasha suggested awhile ago. Probably some Led Zepplin." Yes, he listened to the stuff that Tony played in the workshop; teasing Tony about it was just part of their usual games. "Some of the songs my Ma used to sing to me when I was sick."