page_title: Time point
section_title: Interonset interval
hierarchical_section_title: Time point / Interonset interval
caption_attribution_description: English: Simple quadruple drum pattern: divides four beats into two. Half time: notice the snare moves to beats 3 of measure one and two (beats 3 &amp; 7) while the hi-hat plays only on the quarter notes. Note also, for example, that the quarter notes 'sound like' eighth notes in one giant measure. Created by Hyacinth (talk) 20:12, 1 March 2010 using Sibelius 5.
context_page_description: In music a time point or timepoint is "an instant, analogous to a geometrical point in space". Because it has no duration, it literally cannot be heard, but it may be used to represent "the point of initiation of a single pitch, the repetition of a pitch, or a pitch simultaneity", therefore the beginning of a sound, rather than its duration. It may also designate the release of a note or the point within a note at which something changes. Other terms often used in music theory and analysis are attack point and starting point. Milton Babbitt calls the distance from one time point, attack, or starting point to the next a time-point interval, independent of the durations of the sounding notes which may be either shorter than the time-point interval, or longer. Charles Wuorinen shortens this expression to just time interval. Other writers use the terms attack interval, or, interval of entry, interval of entrance, or starting interval.
context_section_description: 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. A variant of this term is interval of onset.
  For example, two sixteenth notes separated by dotted eighth rest, would have the same interonset interval as between a quarter note and a sixteenth note:
  The concept is often useful for considering rhythms and meters.
caption: Half time drum pattern: the first and second measures have identical time-point, attack, or interonset intervals (About this soundPlay (help·info)) and will sound identical given certain instrumentation and performance practices.
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