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Atime signature (also known asmeter signature,[1]metre signature,[2] andmeasure signature)[3] is an indication inmusic notation that specifies how manynote values of a particular type fit into each measure (bar). The time signature indicates themeter of a musical movement at the bar level.
In a music score the time signature appears as two stacked numerals, such as4
4 (spoken asfour–four time), or a time symbol, such as
(spoken ascommon time). It immediately follows thekey signature (or if there is no key signature, theclef symbol). A mid-score time signature, usually immediately following abarline, indicates a change ofmeter.
Most time signatures are eithersimple (the note values are grouped in pairs, like2
4,3
4, and4
4), orcompound (grouped in threes, like6
8,9
8, and12
8). Less common signatures indicatecomplex,mixed,additive, andirrational meters.

Most time signatures consist of two numerals, one stacked above the other:
For instance,2
4 means twoquarter-notes (crotchets) per bar, while4
8 means foureighth-notes (quavers) per bar. The most common time signatures are2
4,3
4, and4
4.
By convention, two special symbols are sometimes used for4
4 and2
2:
These symbols derive frommensural time signatures, described below.
Simple meters are those whose upper number is 2, 3, or 4, sometimes described asduple meter,triple meter, andquadruple meter respectively.
Incompound meter, the note values specified by the bottom number are grouped into threes, and the upper number is a multiple of 3, such as 6, 9, or 12. The lower number is most commonly an 8 (an eighth-note or quaver): as in9
8 or12
8.
Other upper numbers correspond toirregular meters.
Musical passages commonly feature a recurring pulse, orbeat, usually in the range of 60–140 beats per minute. Depending on the tempo of the music, this beat may correspond to the note value specified by the time signature, or to a grouping of such note values. Most commonly, in simple time signatures, the beat is the same as the note value of the signature, but in compound signatures, the beat is usually adotted note value corresponding to three of the signature's note values. Either way, the next lower note value shorter than the beat is called thesubdivision.
On occasion a bar may seem like one singular beat. For example, a fast waltz, notated in3
4 time, may be described as beingone in a bar. Conversely, at slow tempos, the beat might even be a smaller note value than the one enumerated by the time signature.[example needed]
Mathematically the time signatures of, e.g.,3
4 and3
8 are interchangeable. In a senseall simple triple time signatures, such as3
8,3
4,3
2, etc.—and all compound duple times, such as6
8,6
16 and so on, are equivalent. A piece in3
4 can be easily rewritten in3
8, simply by halving the length of the notes.
![\new Staff <<
\new voice \relative c' {
\clef percussion
\time 3/4
\tempo 4 = 100
\stemDown \repeat volta 2 { g4 d' d }
\time 3/8
\tempo 8 = 100
\stemDown \repeat volta 2 { g,8 d' d }
}
\new voice \relative c'' {
\override NoteHead.style = #'cross
\stemUp \repeat volta 2 { a8[ a] a[ a] a[ a] }
\stemUp \repeat volta 2 { a16 a a a a a }
}
>>](/image.pl?url=https%3a%2f%2fen.wikipedia.org%2f%2fupload.wikimedia.org%2fscore%2fh%2ft%2fht6hxyxpr9v3xb0cpjv683icswka64s%2fht6hxyxp.png&f=jpg&w=240)
Other time signature rewritings are possible: most commonly a simple time-signature with triplets translates into a compound meter.

The choice of time signature in these cases is largely a matter of tradition. Particular time signatures are traditionally associated with different music styles—it would seem strange to notate a conventionalrock song in4
8 or4
2, rather than4
4.
In the examples below,bold denotes the primary stress of the measure, anditalics denote a secondary stress. Syllables such as "and" are frequently used for pulsing in between numbers.
Simple:3
4 is a simpletriple meter time signature that represents three quarter notes (crotchets), usually perceived as three beats. In this case the subdivision would be the eighth note (quaver). It is felt as
Compound: Most often,6
8 is felt as two beats, each being a dotted quarter note (crotchet), and each containing subdivisions of three eighth notes (quavers). It is felt as
The table below shows the characteristics of the most frequently used time signatures.
| Simple time signatures | |||
|---|---|---|---|
| Time signature | Common uses | Simple drum pattern | Video representation |
| 4 4 or (quadruple) | Common time: Widely used inclassical music and most forms ofpopular music. Most common time signature inrock,blues,country,funk, andpop.[4] | ![]() | |
| 2 2 or (duple) | Alla breve,cut time: Used formarches and fast orchestral music. | ![]() | |
| 2 4 (duple) | Used forpolkas,galops,marches, and many styles ofLatin music (includingbolero,cumbia, andmerengue). | ![]() | |
| 3 4 (triple) | Used forwaltzes,minuets,scherzi,polonaises,mazurkas, country & western ballads, R&B, and some pop | ![]() | |
| 3 8 (triple) | Also used for the above but usually suggests higher tempo or shorterhypermeter. Sometimes preferred for certain folk dances such ascachucha | ![]() | |
| Compound time signatures | |||
| Time signature | Common uses | Simple drum pattern | Video representation |
| 6 8 (duple) | Doublejigs,jotas,zortzikos, polkas,sega,salegy,tarantella,marches,barcarolles,loures, and some rock music.Anapestic tetrameter poetry also fits into6 8 time when said aloud. | ![]() | |
| 9 8 (triple) | Compound triple time: Used inslip jigs; otherwise occurring rarely ("The Ride of the Valkyries",Tchaikovsky'sFourth Symphony, and the final movement ofJ.S. Bach'sViolin Concerto in A minor (BWV 1041) are familiar examples.Debussy's "Clair de lune" and the opening bars ofPrélude à l'après-midi d'un faune are also in9 8) | ![]() | |
| 12 8 (quadruple) | Also common in slowerblues (where it is called ashuffle) anddoo-wop; also used more recently in rock music. Can also be heard in some jigs like "The Irish Washerwoman". This is also the time signature ofScene by the Brook, the second movement ofBeethoven'sPastoral Symphony. | ![]() | |
While changing the bottom number and keeping the top number fixed only formally changes notation, without changing meaning –3
8,3
4,3
2, and3
1 are all three beats to a meter, just noted with eighth notes, quarter notes, half notes, or whole notes – these conventionally imply different performance and different tempi. Conventionally, larger numbers in the bottom correspond to faster tempi and smaller numbers correspond to slower tempi. This convention is known astempo giusto, and means that the tempo of each note remains in a narrower, "normal" range. For illustration, a quarter note might correspond to 60–120 bpm (quintuplet 75–150, triplet 90–180 and septuplet 105–210), a half note to 30–60 bpm (triplet 45–90), a whole note to 15–30 bpm, and an eighth note to 120–240 bpm; these are not strict, but show an example of "normal" ranges.
This convention dates to theBaroque era, when tempo changes were indicated by changing time signature during the piece, rather than by using a single time signature and changing tempo marking.[5]
Signatures that do not fit the usual simple or compound categories are calledcomplex,asymmetric,irregular,unusual, orodd—though these are broad terms, and usually a more specific description is any meter which combines both simple and compound beats.[6][7]
Irregular meters are common in some non-Western music, and in ancient Greek music such as theDelphic Hymns to Apollo, but the corresponding time signatures rarely appeared in formal written Western music until the 19th century. Early anomalous examples appeared in Spain between 1516 and 1520,[8] plus a small section in Handel's operaOrlando (1733).
The third movement ofFrédéric Chopin'sPiano Sonata No. 1 (1828) is an early, but by no means the earliest, example of5
4 time in solo piano music.Anton Reicha's Fugue No. 20 from hisThirty-six Fugues, published in 1803, is also for piano and is in5
8. Thewaltz-like second movement of Tchaikovsky'sPathétique Symphony (shown below), often described as a "limping waltz",[9] is a notable example of5
4 time in orchestral music.
Examples from20th-century classical music include:
In the Western popular music tradition, unusual time signatures occur as well, withprogressive rock in particular making frequent use of them. The use of shifting meters inThe Beatles' "Strawberry Fields Forever" and the use ofquintuple meter in their "Within You, Without You" are well-known examples,[10] as isRadiohead's "Paranoid Android" (includes7
8).[11]
Paul Desmond'sjazz composition "Take Five", in5
4 time, was one of a number of irregular-meter compositions thatThe Dave Brubeck Quartet played. They played other compositions in11
4 ("Eleven Four"),7
4 ("Unsquare Dance"), and9
8 ("Blue Rondo à la Turk"), expressed as2+2+2+3
8. "Blue Rondo à la Turk" is an example of a signature that, despite appearing merely compound triple, is actually more complex. Brubeck's title refers to the characteristicaksak meter of the Turkishkarşılama dance.[12]
However, such time signatures are only unusual in most Western music. Traditionalmusic of the Balkans uses such meters extensively.Bulgarian dances, for example, include forms with 5, 7, 9, 11, 13, 15, 22, 25 and other numbers of beats per measure. These rhythms are notated asadditive rhythms based on simple units, usually 2, 3 and 4 beats, though the notation fails to describe themetric "time bending" taking place, orcompound meters. SeeAdditive meters below.
Some video samples are shown below.
4 at 60bpm | 4 at 60 bpm | 4 at 60 bpm |
While time signatures usually express a regular pattern of beat stresses continuing through a piece (or at least a section), sometimes composers change time signatures often enough to result in music with an extremely irregular rhythm. The time signature may switch so much that a piece may not be best described as being in one meter, but rather as having a switching mixed meter. In this case, the time signatures are an aid to the performers and notnecessarily an indication of meter. The Promenade fromModest Mussorgsky'sPictures at an Exhibition (1874) is a good example. The opening measures are shown below:
Igor Stravinsky'sThe Rite of Spring (1913) is famous for its "savage" rhythms. Five measures from "Sacrificial Dance" are shown below:
In such cases, a convention that some composers follow (e.g.,Olivier Messiaen, in hisLa Nativité du Seigneur andQuatuor pour la fin du temps) is to simply omit the time signature.Charles Ives'sConcord Sonata has measure bars for select passages, but the majority of the work is unbarred.
Some pieces have no time signature, as there is no discernible meter. This is sometimes known asfree time. Sometimes one is provided (usually4
4) so that the performer finds the piece easier to read, and simply has "free time" written as a direction. Sometimes the wordFREE is written downwards on the staff to indicate the piece is in free time.Erik Satie wrote many compositions that are ostensibly in free time but actually follow an unstated and unchanging simple time signature. Later composers used this device more effectively, writing music almost devoid of a discernibly regular pulse.
If two time signatures alternate repeatedly, sometimes the two signatures are placed together at the beginning of the piece or section, as shown below:

To indicate more complex patterns of stresses, such asadditive rhythms, more complex time signatures can be used. Additive meters have a pattern ofbeats that subdivide into smaller, irregular groups. Such meters are sometimes calledimperfect, in contrast toperfect meters, in which thebar is first divided into equal units.[13]
For example, the time signature3+2+3
8 means that there are 8 quaver beats in the bar, divided as the first of a group of three eighth notes (quavers) that are stressed, then the first of a group of two, then first of a group of three again. The stress pattern is usually counted as
This kind of time signature is commonly used to notate folk and non-Western types of music. In classical music,Béla Bartók andOlivier Messiaen have used such time signatures in their works. The first movement ofMaurice Ravel'sPiano Trio in A Minor is written in8
8, in which the beats are likewise subdivided into3+2+3 to reflectBasque dance rhythms.
RomanianmusicologistConstantin Brăiloiu had a special interest in compound time signatures, developed while studying thetraditional music of certain regions in his country. While investigating the origins of such unusual meters, he learned that they were even more characteristic of the traditional music of neighboring peoples (e.g., theBulgarians). He suggested that such timings can be regarded as compounds of simple two-beat and three-beat meters, where an accent falls on every first beat, even though, for example inBulgarian music, beat lengths of 1, 2, 3, 4 are used in the metric description. In addition, when focused only on stressed beats, simple time signatures can count as beats in a slower, compound time. However, there are two different-length beats in this resulting compound time, a one half-again longer than the short beat (or conversely, the short beat is2⁄3 the value of the long). This type of meter is calledaksak (the Turkish word for "limping"),impeded,jolting, orshaking, and is described as anirregular bichronic rhythm. A certain amount of confusion for Western musicians is inevitable, since a measure they would likely regard as7
16, for example, is a three-beat measure inaksak, with one long and two short beats (with subdivisions of2+2+3,2+3+2, or3+2+2).[14]
Folk music may make use of metric time bends, so that the proportions of the performed metric beat time lengths differ from the exact proportions indicated by the metric. Depending on playing style of the same meter, the time bend can vary from non-existent to considerable; in the latter case, some musicologists may want to assign a different meter. For example, the Bulgarian tune "Eleno Mome" is written in one of three forms: (1)7 = 2+2+1+2, (2)13 = 4+4+2+3, or (3)12 = 3+4+2+3, but an actual performance (e.g., "Eleno Mome"[15][original research?]) may be closer to4+4+2+3.[clarification needed] The Macedonian3+2+2+3+2 meter is even more complicated, with heavier time bends, and use of quadruples on the threes. The metric beat time proportions may vary with the speed that the tune is played. The SwedishBoda Polska (Polska from the parish Boda) has a typical elongated second beat.
In Western classical music, metric time bend is used in the performance of theViennese waltz. Most Western music uses metric ratios of 2:1, 3:1, or 4:1 (two-, three- or four-beat time signatures)—in other words, integer ratios that make all beats equal in time length. So, relative to that, 3:2 and 4:3 ratios correspond to very distinctive metric rhythm profiles. Complex accentuation occurs in Western music, but assyncopation rather than as part of the metric accentuation.[citation needed]
Brăiloiu borrowed a term fromTurkish medieval music theory:aksak. Such compound time signatures fall under the "aksak rhythm" category that he introduced along with a couple more that should describe the rhythm figures in traditional music.[16] The term Brăiloiu revived had moderate success worldwide, but in Eastern Europe it is still frequently used. However, aksak rhythm figures occur not only in a few European countries, but on all continents, featuring various combinations of the two and three sequences. The longest are in Bulgaria. The shortest aksak rhythm figures follow the five-beat timing, comprising a two and a three (or three and two).
Some video samples are shown below.
8 at 120bpm |
A method to create meters of lengths of any length has been published in the Journal of Anaphoria Music Theory[17] and Xenharmonikon 16[18] using both those based on the Horograms ofErv Wilson and Viggo Brun's algorithm written byKraig Grady.

Irrational time signatures (rarely, "non-dyadic time signatures") are used for so-calledirrational bar lengths,[19] that have adenominator that is not apower of two (1, 2, 4, 8, 16, 32, etc.). These are based on beats expressed in terms of fractions of full beats in the prevailing tempo—for example3
10 or6
7.[19] For example, where4
4 implies a bar construction of four quarter-parts of a whole note (i.e., four quarter notes),4
3 implies a bar construction of four third-parts of it. These signatures are of utility only when juxtaposed with other signatures with varying denominators; a piece written entirely in4
3 could be more legibly written out in4
4.


According toBrian Ferneyhough,metric modulation is "a somewhat distant analogy" to his own use of "irrational time signatures" as a sort of rhythmic dissonance.[19] It is disputed whether the use of these signatures makes metric relationships clearer or more obscure to the musician; it is always possible to write a passage using non-irrational signatures by specifying a relationship between some note length in the previous bar and some other in the succeeding one. Sometimes, successive metric relationships between bars are so convoluted that the pure use of irrational signatures would quickly render the notation extremely hard to penetrate.
Historically, this device has been prefigured wherever composers wrotetuplets. For example, a2
4 bar of 3 triplet quarter notes could be written as a bar of3
6.Henry Cowell's piano pieceFabric (1920) employs separate divisions of the bar (1 to 9) for the threecontrapuntal parts, using a scheme of shapednoteheads to visually clarify the differences, but the pioneering of these signatures is largely due toBrian Ferneyhough, who says that he finds that "such 'irrational' measures serve as a useful buffer between local changes of event density and actual changes of basetempo".[19]Thomas Adès has also used them extensively—for example inTraced Overhead (1996), the second movement of which contains, among more conventional meters, bars in such signatures as2
6 and9
14.
Notationally, rather than using Cowell's elaborate series of notehead shapes, the same convention has been invoked as when normal tuplets are written; for example, one beat in4
5 is written as a normal quarter note, four quarter notes complete the bar, but the whole bar lasts only4⁄5 of a referencewhole note, and a beat1⁄5 of one (or4⁄5 of a normal quarter note). This is notated in exactly the same way that one would write if one were writing the first four quarter notes of five quintuplet quarter notes.
Some video samples are shown below.
These video samples show two time signatures combined to make apolymeter, since4
3, in isolation, is identical to4
4.
4 and4 3 played together has three beats of4 3 to four beats of4 4 | 6 and3 4 played together has six beats of2 6 to four beats of3 4 | 5 and2 3 played together has five beats of2 5 to three beats of2 3. The displayed numbers count the underlyingpolyrhythm, which is 5:3 |
Some composers have used fractional beats: for example, the time signature2+1⁄2
4 (equivalent to5
8) appears inCarlos Chávez's Piano Sonata No. 3 (1928) IV, m. 1. Both2+1⁄2
4 and1+1⁄2
4 appear in the fifth movement ofPercy Grainger'sLincolnshire Posy.

Music educatorCarl Orff proposed replacing the lower number of the time signature with an actual note image, as shown at right. This system eliminates the need for compound time signatures, which are confusing to beginners. While this notation has not been adopted by music publishers generally (except in Orff's own compositions), it is used extensively in music education textbooks. Similarly, American composersGeorge Crumb andJoseph Schwantner, among others, have used this system in many of their works.Émile Jaques-Dalcroze proposed this in his 1920 collection,Le Rythme, la musique et l'éducation.[20]
Another possibility is to extend the barline where a time change is to take place above the top instrument's line in a score and to write the time signature there, and there only, saving the ink and effort that would have been spent writing it in each instrument's staff.Henryk Górecki'sBeatus Vir is an example of this. Alternatively, music in a large score sometimes has time signatures written as very long, thin numbers covering the whole height of the score rather than replicating it on each staff; this is an aid to the conductor, who can see signature changes more easily.
In themensural notation of the 14th, 15th and 16th centuries there are nobar lines, and the four basicmensuration signs
,
,
,
indicate the normal ratio ofduration between differentnote values. Unlike modern notation, the subdivisions could be either 2:1 or 3:1. The relation between thebreve
and thesemibreve
was calledtempus, and could be perfect (triple 3:1 indicated by circle) or imperfect (duple 2:1, with broken circle), while the relation between thesemibreve and theminim
was calledprolatio and could be major (3:1 orcompound, indicated by dot) or minor (2:1 orsimple meter).
Modern transcriptions often reduce note values 4:1, such that
In mensural notation actual note values depend not only on the prevailing mensuration, but on rules forimperfection and alteration, with ambiguous cases using a dot of separation, similar in appearance but not always in effect to the moderndot of augmentation.
| Proportion | Notated values | equivalent to | Notated values |
|---|---|---|---|
Besides showing the organization of beats withmusical meter, the mensuration signs discussed above have a second function, which is showing tempo relationships between one section to another, which modern notation can only specify withtuplets ormetric modulations. This is a fraught subject, because the usage has varied with both time and place:Charles Hamm[22] was even able to establish a rough chronology of works based on three distinct usages of mensural signs over the career ofGuillaume Dufay (1397(?) – 1474). By the end of the sixteenth centuryThomas Morley was able to satirize the confusion in an imagined dialogue:
it was a world to hear them wrangle, every one defending his own for the best. "What? You keep not time in your proportions." "You sing them false. What proportion is this?" "Sesquipaltry." "Nay, you sing you know not what; it would seem you came lately from a barber's shop where you had 'Gregory Walker' or aCurranta played in the new Proportions by them lately found out, called 'Sesquiblinda' and 'Sesquihearkenafter'."
- Plaine and Easie Introduction to Practicall Musicke (1597)[23]
In general though, a slash or the numeral 2 shows a doubling of tempo, and paired numbers (either side by side or one atop another) show ratios instead of beats per measure over note value: in early music contexts4
3 for example is unrelated to 'third-notes'.[24]
A few common signs are shown:[25]
In particular, when the sign
was encountered, thetactus (beat) changed from the usual whole note (semibreve) to the double whole note (breve), a circumstance calledalla breve. This term has been sustained to the present day, and though now it means the beat is ahalf note (minim), in contradiction to the literal meaning of the phrase, it still indicates that thetactus has changed from a short to a doubled value.
Certain composers delighted in creating mensuration canons, "puzzle" compositions that were intentionally difficult to decipher.[26]
Irregular bars are a change in time signature normally for only one bar. Such a bar is most often a bar of3
4,5
4 or2
4 in a4
4 composition, or a bar of4
4 in a3
4 composition, or a bar of5
8 in a6
8 composition.
If a song is entirely in4
4, a change to3
4 will make the song feel like it has skipped a beat. The opposite is true for5
4, where it feels like the song adds a beat. If a song changes to2
4 is will make it feel like that bar is half as long as all the others.[27][28]
Some popular examples include "Golden Brown" byThe Stranglers (4
4 in a3
4 composition), "I Love Rock 'n' Roll" originally byThe Arrows (7
4 in a4
4 composition), "Hey Ya!" byOutkast (2
4 in a4
4 composition), and "Wuthering Heights" byKate Bush (different kinds of irregular bars in a4
4 composition).
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