Metre (music)

In music, metre refers to regularly recurring patterns of accents, such as downbeats and beats. While rhythm describes the specific pattern of sounds, metre is the underlying framework of pulses. Even when a performer does not physically sound every beat, the metre is implied by the performer and expected by the listener.

This process involves our initial perception and subsequent anticipation of a series of beats. We abstract these beats from the "rhythm surface" of the music as it unfolds in time. This ability to sense a metric structure is a foundation of instinctive human musical participation. It is similar to how we divide identical clock-ticks into a "tick–tock" pattern.

Metric structure is created by the interaction of two levels of motion. A faster level provides the steady pulse, while a slower level organizes those pulses into repetitive groups. This creates a metric hierarchy. Once this hierarchy is established, listeners tend to maintain that organization as long as minimal evidence is present.

To identify a metre, one can take an accented beat as the first pulse and count the pulses until the next accent occurs. This creates a "pulse-group" that functions much like a foot in poetry. Metrical rhythm is the most common class in Western music. In this system, each time value is a multiple or fraction of a fixed unit, known as a beat.

Musicians use different classes of rhythm to organize time. Metrical rhythm uses regular, recurring accents to provide systematic grouping into bars. Measured rhythm, or additive rhythm, uses time values that are multiples of a specified unit, but it lacks regularly recurring accents. Free rhythm occurs when time values are not based on any fixed unit at all. Because free rhythm lacks a fixed unit, regular accents are not possible. Some music, such as certain chants or the Honkyoku repertoire for shakuhachi, is considered ametric. In Italian, the term "senza misura" means "without metre," indicating a piece is played without a fixed beat.

Metres are often classified by the number of beats found in each measure. Duple metre divides each measure into two beats, while quadruple metre divides it into four. For example, a 2/4 time signature contains two quarter-note beats per bar. Triple metre divides each bar into three beats, such as a 3/4 time signature. Some metres contain more than four beats, known as quintuple (5), sextuple (6), or septuple (7) metres. In classical music theory, it is often presumed that only divisions of two or three are perceptually valid. Therefore, a 5/4 metre might be perceived as a combination of 3/4 and 2/4 metres.

Another way to classify metre is by how the beats are subdivided. Simple metre occurs when each beat divides naturally into two equal parts. For example, in 3/4 time, each of the three quarter-note beats divides into two eighth notes. Compound metre occurs when each beat divides into three equal parts, creating a triple pulse. This is often seen in time signatures like 6/8, 9/8, or 12/8.

Compound metre is frequently associated with "lilting" and dancelike qualities. Many folk dances and Baroque dances, such as the gigue or the courante, utilize compound time. Conductors often provide only two beats per bar when conducting in 6/8, though all six beats may be performed if the tempo is very slow.

Western music inherited much of its metrical concept from poetry. In poetry, metre denotes the number of lines, the number of syllables per line, and the arrangement of accented and unaccented syllables. The first coherent system of rhythmic notation in modern Western music was based on rhythmic modes. These modes were derived from the quantitative metre of classical ancient Greek and Latin poetry. Later, dance music like the pavane or galliard used musical phrases to accompany fixed sequences of steps. The English word "measure" originally meant an exact amount of time. It eventually came to represent a poetic rhythm, a bar of music, or an entire melodic verse.

Metre also provides a vital link between song, dance, and structure. In traditional songs, the arrangement of metrical figures into phrases and stanzas creates the "time pattern" of the song. Many songs use ballad metre, a four-line verse form with an 8–6–8–6 syllable count. This shared structure allows different melodies to be interchangeable. For example, the hymn "Amazing Grace" can be sung to the melody of "The House of the Rising Sun." In dance, metre is essential for recognizable patterns. The tango, for instance, is danced in 2/4 time at approximately 66 beats per minute.

This structure allows dancers to coordinate "slow" and "quick" steps within the musical framework.