Milton Babbitt’s It takes twelve to tango (1984) has a subdivision series that unfolds in two dimensions: globally in the first beat of the 2/4 meter, and locally in the second beat. Though the eight subdivision series expressed in the second beat mostly proceed at the rate of one subdivision per measure, occasionally a subdivision will be repeated in two consecutive measures.
Attempts to interpret these duplicated subdivisions reveal intersections between the subdivision series and a wide variety of other aspects of the piece, including the pitch-class array, hypermeter, and registral gestures. These non-systematic explanations illuminate the meaning and power of the systematic aspects of Babbitt’s music.
This according to “Duplicated subdivisions in Babbitt’s It takes twelve to tango” by Zachary Bernstein (Music theory online XXVII/2 [July 2011]).
Today would have been Babbitt’s 100th birthday! Below, Edward Neeman does the twelve-tone tango.