https://www.youtube.com/watch?v=LSz99Hd0uvI
I met this fine gentleman at the FRC World Championship. He had a setup that performed analysis on incoming sound and graphed it using the lights on his hat. This, combined with the other flashing lights on his person, were powered by a battery in his pocket. Thankfully, he did not catch fire, so this video did not become "Matt cooks a corndog."