About that Mozart-crazed UFO, Tom Ziegler writes to say that he got a closer look, and the disruption emanated not from something spaceship-sized but from a nasty little pocket gizmo belonging to a flustered couple in the Third Tier.
They tried to shut whatever it was off and when that failed, the man and the woman were passing it back and forth and trying to cover it with their coats. That may explain why you thought it was moving. Whatever it was had a flashing orange light and sounded like a motion detector. In any event, they finally stifled the thing and sat there enduring the stares. What's strange is that I kept hearing the sound even though it was shut off. In some weird way, the overtones of the mass matched the sounds of the device.
Maybe it's time to update the no-beeping-electronics speech: "Please silence your cell phones, disable portable air-raid alarms, leave home security systems at home, and chloroform your Dobermans. The hall is perfectly safe."