it may sound immediately), and subsequent numbers which descend as in the following measure (if three follows four it must necessarily wait for the next appearance of time-point three). Babbitt uses time points in Partitions (1957), All Set (1957), and Post-Partitions (1966), as well as in Phonemena (1969–70), String Quartets No. 3 (1969–70) and No. 4 (1970), Arie da capo (1974), My Ends Are My Beginnings (1978), and Paraphrases (1979). Charles Wuorinen has also developed an approach to the time-point system, which differs greatly from Babbitt's. Sources Sources Further reading Johnson, William Marvin (1984). "Timepoint Sets and Meter". Perspectives of New Music 23, no. 1 (Fall–Winter): 278–297. Oxford, Parncutt and Mc Pherson (eds.) (2002). The Science and Psychology of Music Performance, p. 200–202. Scotto, Ciro (1988). "Preparing a Performance of Babbitt's Arie da Capo". Perspectives of New Music 26, no. 2 (Summer): 6–24. External links "interonset interval (IOI)" archived on 31 Dec 2013, Rhythm and Meter Bibliography and Glossary at the School of Music at Indiana University Rhythm and meter Serialism