Replying to Interviewing Street Performers, T2i Sound Help Please

I have been asked to film the interviewing of street performers in Denver and Boulder this weekend. I film with a T2i, and have no external mic, and obviously downtown Denver is a very loud place, and obviously the stock sound recording on the T2i is that of a cell phone essentially. I am worried that the background noise will drown out the sound of the interviewer. I am going to use a song for most of it, and the song will fade quieter when the performer is being interviewed. Not really sure what else to say, I'm kind of pulling for straws here. Anybody have any suggestions?