What are those drums?

The guide turned to him and said "No worry. Drums OK, but very bad when they stop." They both went ghostly pale when the drums suddenly stopped.
The guide crouched in the belly of the canoe and covered his ears.
"Do as I do! Very important!" intoned the guide with great urgency.
"Why? What does this mean?" asked the panicked anthropologist.
"Drums stop! Next come guitar solo!"
Originally published February 23, 2003.