Editing Metre (music) (section)

==Metric structure==
<!--[[Subdivision (meter)]], [[Subdivision (music)]], [[Division level]], [[Metric hierarchy]], and [[multiple level]] redirect directly here-->

The term ''metre'' is not very precisely defined.{{sfn|Scholes|1977}}  [[Stewart Macpherson|Stewart MacPherson]] preferred to speak of "time" and "rhythmic shape",{{sfn|MacPherson|1930|loc=3}} while [[Imogen Holst]] preferred "measured rhythm".{{sfn|Holst|1963|loc=17}} However, Justin London has written a book about musical metre, which "involves our initial perception as well as subsequent anticipation of a series of beats that we abstract from the rhythm surface of the music as it unfolds in time".{{sfn|London|2004|loc=4}} This "perception" and "abstraction" of rhythmic bar is the foundation of human instinctive musical participation, as when we divide a series of identical clock-ticks into "tick–tock–tick–tock".{{sfn|Scholes|1977}} "Rhythms of recurrence" arise from the interaction of two levels of motion, the faster providing the pulse and the slower organizing the beats into repetitive groups.{{sfn|Yeston|1976|loc=50–52}} In his book ''The Rhythms of Tonal Music'', Joel Lester notes that, "[o]nce a metric hierarchy has been established, we, as listeners, will maintain that organization as long as minimal evidence is present".{{sfn|Lester|1986|loc=77}}

[[File:Metric levels.svg|thumb|350px|left|Metric levels: beat level shown in middle with division levels above and multiple levels below.]]
"''Meter'' may be defined as a regular, recurring pattern of strong and weak beats. This recurring pattern of durations is identified at the beginning of a composition by a meter signature (time signature). ... Although meter is generally indicated by time signatures, it is important to realize that meter is not simply a matter of notation".{{sfn|Benward and Saker|2003|loc=9}} A definition of musical metre requires the possibility of identifying a repeating pattern of accented pulses – a "pulse-group" – which corresponds to the [[foot (poetry)|foot]] in poetry.{{cn|date=October 2020}} Frequently a pulse-group can be identified by taking the accented beat as the first pulse in the group and [[counting (music)|counting]] the pulses until the next accent.{{sfn|MacPherson|1930|loc=5}}{{sfn|Scholes|1977}}

Frequently metres can be subdivided into a pattern of duples and triples.{{sfn|MacPherson|1930|loc=5}}{{sfn|Scholes|1977}} 

For example, a {{Music|time|3|4}} metre consists of three units of a {{Music|time|2|8}} pulse group, and a {{Music|time|6|8}} metre consists of two units of a {{Music|time|3|8}} pulse group. In turn, metric bars may comprise 'metric groups' - for example, a musical phrase or melody might consist of two bars x {{Music|time|3|4}}.{{sfn|Cooper|Meyer|1960|p={{page needed|date=August 2021}}}}

The level of musical organisation implied by musical metre includes the most elementary levels of [[form (music)|musical form]].{{sfn|MacPherson|1930|loc=3}} Metrical rhythm, measured rhythm, and free rhythm are general classes of rhythm and may be distinguished in all aspects of temporality:{{sfn|Cooper|1973|loc=30}}
* '''Metrical rhythm''', by far the most common class in Western music, is where each time value is a multiple or fraction of a fixed unit (beat, see paragraph below), and normal [[Accent (music)|accents]] reoccur regularly, providing systematic grouping ([[Bar (music)|bars]], [[divisive rhythm]]).
* '''Measured rhythm''' is where each time value is a multiple or fraction of a specified time unit but there are not regularly recurring accents ([[additive rhythm]]).
* [[Free time (music)|'''Free rhythm''']] is where the time values are not based on any fixed unit; since the time values lack a fixed unit, regularly recurring accents are no longer a possibility.
Some music, including [[chant]], has freer rhythm, like the rhythm of [[prose]] compared to that of [[Verse (poetry)|verse]].{{sfn|Scholes|1977}} Some music, such as some graphically scored works since the 1950s and [[World music|non-European music]] such as [[Honkyoku]] repertoire for [[shakuhachi]], may be considered ametric.{{sfn|Karpinski|2000|loc=19}} The music term ''senza misura'' is Italian for "without metre", meaning to play without a beat, using [[time]] (e.g. seconds elapsed on an ordinary clock) if necessary to determine how long it will take to play the bar.{{sfn|Forney and Machlis|2007|loc=?}}{{Page needed|date=December 2009}}

Metric structure includes metre, [[tempo]], and all [[rhythm]]ic aspects that produce temporal regularity or structure, against which the foreground details or [[Duration (music)|durational pattern]]s of any piece of music are projected.{{sfn|Wittlich|1975|loc=ch. 3}} Metric levels may be distinguished: the [[beat level]] is the metric level at which pulses are heard as the basic time unit of the piece.{{cn|date=October 2020}} Faster levels are division levels, and slower levels are multiple levels.{{sfn|Wittlich|1975|loc=ch. 3}} A [[rhythmic unit]] is a durational pattern which occupies a period of time equivalent to a [[Pulse (music)|pulse]] or pulses on an underlying metric level.{{cn|date=October 2020}}