Lindsey Horn, a member of the staff at Surratt House, is our Herold expert; and I believe she found reference to the bells tolling at the nearby church in the David Rankin Barbee Papers. She believes that the tolling was strictly announcing the hour - not the execution.
I also went to American Brutus and checked both text and the extensive notes to see if Kauffman included any reference to drums or a band. I see no mention, and if that escaped his attention, I would be very surprised.