Here's a new function a bit similar to my old "add-interval-if-length" function but bit more sophisticated. It use gen-chord3 to create chord on defined length.   ;;; ============================================== ;;; UTILITY FUNCTIONS ;;; (defun make-chord-if-length-aux (omn &key (test #'>) (length-val 1/8) (interval-list '((4 7)(7 12))) (cycle t)(relative nil) seed) (setf seed (rnd-seed seed)) (let ((s-events (single-events omn))) (loop for e in s-events