Transcript for Impromptu National Anthem duet recorded for virtual commencement
Liberty. Liberty. Liberty. Liberty. Finally tonight here, America strong. The student about to graduate, about to sing, and then this. O say can you see Reporter: Madisen Hallberg was preparing to sing the national anthem for her virtual commencement from Portland state university, when a man walking by heard her warming up and signaled to the crew he'd like to join her. And so he did. And the rockets' red glare the bombs bursting in air gave proof through the night that our flag was still there Reporter: Tonight, madisen saying she was moved by the moment she was suddenly sharing. Hi, David. It's also symbolic for what we need to do as a people and as a community is to not try to out-sing the person next to you, but blend with them and harmonize with them. Reporter: That man who was walking by, Emanuel henreid, is a trained opera singer. And tonight, he says he is grateful she was up for that duet. It was a beautiful moment that we shared and in that moment, I realized that it's essential for us to raise our voices in empowerment and in love with one another. And the home of the brave The unexpected duet for graduation and we loved it and what it shows. I'm David Muir. I'll see you tomorrow.
This transcript has been automatically generated and may not be 100% accurate.