When I was a student at SanDeigo State and pupil of Burt Turetzky back in the early 80's I saw Burt T play a piece called "Failing" by Tom Johnson.
He had 12 music stands placed in a row on stage with like 24
continuous pages of music. The piece was written for spoken
word and dbl bass.
So going from left to right moving his bass along with him I heard
him play very difficult bass lines and recite the words and play
hamonics and tap the wood in different places like conga's and make it all happen at the same time. At times he would take his middle finger and push it along the top of the bass like a drummer
does to vibrate the head of a drum.
It sounded like three players up there. It was amazing watching
him do it. Impecable playing and dexterity.