Time point

The corresponding term used in acoustics and audio engineering to describe the initiation of a sound is onset, and the interonset interval or IOI is the time between the beginnings or attack points of successive events or notes, the interval between onsets, not including the duration of the events.

[12] In serial music a time-point set, proposed in 1962 by Milton Babbitt,[14] is a temporal order of pitches in a tone row which indicates the instants at which the notes start.

This has certain advantages over a duration scale or row built from multiples of a unit,[15] derived from Olivier Messiaen.

Then, pitch number is interpretable as the point of initiation of a temporal event, that is, as a time-point number.For example, a measure may be divided into twelve metrical positions.

[17] Babbitt uses time points in Partitions (1957), All Set (1957), and Post-Partitions (1966),[18] as well as in Phonemena (1969–70), String Quartets No.