Rhythm

Rhythm (from Greek ῥυθμός, rhythmos, "any regular recurring motion, symmetry"[1]) generally means a "movement marked by the regulated succession of strong and weak elements, or of opposite or different conditions".

[2] This general meaning of regular recurrence or pattern in time can apply to a wide variety of cyclical natural phenomena having a periodicity or frequency of anything from microseconds to several seconds (as with the riff in a rock music song); to several minutes or hours, or, at the most extreme, even over many years.

The Oxford English Dictionary defines rhythm as "The measured flow of words or phrases in verse, forming various patterns of sound as determined by the relation of long and short or stressed and unstressed syllables in a metrical foot or line; an instance of this".

For example, architects often speak of the rhythm of a building, referring to patterns in the spacing of windows, columns, and other elements of the façade.

[citation needed] In recent years, rhythm and meter have become an important area of research among music scholars.

Recent work in these areas includes books by Maury Yeston,[6] Fred Lerdahl and Ray Jackendoff,[7] Jonathan Kramer, Christopher Hasty,[8] Godfried Toussaint,[9] William Rothstein,[10] Joel Lester,[11]Guerino Mazzola and Steffen Krebber.

[12] In his television series How Music Works, Howard Goodall presents theories that human rhythm recalls the regularity with which we walk and the heartbeat.

Yet other researchers suggest that since certain features of human music are widespread, it is "reasonable to suspect that beat-based rhythmic processing has ancient evolutionary roots".

[15] The "perception" and "abstraction" of rhythmic measure is the foundation of human instinctive musical participation, as when we divide a series of identical clock-ticks into "tick-tock-tick-tock".

[16][17] Joseph Jordania recently suggested that the sense of rhythm was developed in the early stages of hominid evolution by the forces of natural selection.

Musical cultures that rely upon such instruments may develop multi-layered polyrhythm and simultaneous rhythms in more than one time signature, called polymeter.

[27] The "beat" pulse is not necessarily the fastest or the slowest component of the rhythm but the one that is perceived as fundamental: it has a tempo to which listeners entrain as they tap their foot or dance to a piece of music.

[27] Maury Yeston clarified "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.

These contrasts naturally facilitate a dual hierarchy of rhythm and depend on repeating patterns of duration, accent and rest forming a "pulse-group" that corresponds to the poetic foot.

[35] Curtis Roads[39] takes a wider view by distinguishing nine-time scales, this time in order of decreasing duration.

The first two, the infinite and the supra musical, encompass natural periodicities of months, years, decades, centuries, and greater, while the last three, the sample and subsample, which take account of digital and electronic rates "too brief to be properly recorded or perceived", measured in millionths of seconds (microseconds), and finally the infinitesimal or infinitely brief, are again in the extra-musical domain.

As shown in the bottom row of the table, the rhythm without pitch requires fewer bytes if it is "perceived" as it is, without repetitions and tempo leaps.

Generally speaking, the more redundant the "musical support" of a rhythmic pattern, the better its recognizability under augmentations and diminutions, that is, its distortions are perceived as tempo variations rather than rhythmic changes: By taking into account melodic context, homogeneity of accompaniment, harmonic pulsation, and other cues, the range of admissible tempo deviations can be extended further, yet still not preventing musically normal perception.

[42] Such tempo deviations are strictly prohibited, for example, in Bulgarian or Turkish music based on so-called additive rhythms with complex duration ratios, which can also be explained by the principle of correlativity of perception.

[48] Metrical or divisive rhythm, by far the most common in Western music calculates each time value as a multiple or fraction of the beat.

[51] This concept was concurrently defined as "attack point rhythm" by Maury Yeston in 1976 as "the extreme rhythmic foreground of a composition – the absolute surface of articulated movement".

[citation needed] The debate about the appropriateness of staff notation for African music is a subject of particular interest to outsiders while African scholars from Kyagambiddwa to Kongo have, for the most part, accepted the conventions and limitations of staff notation, and produced transcriptions to inform and enable discussion and debate.

Moral values underpin a musical system based on repetition of relatively simple patterns that meet at distant cross-rhythmic intervals and on call-and-response form.

Sheila Chandra, an English pop singer of Indian descent, made performances based on her singing these patterns.

In the 20th century, composers like Igor Stravinsky, Béla Bartók, Philip Glass, and Steve Reich wrote more rhythmically complex music using odd meters, and techniques such as phasing and additive rhythm.

Narmour[58] describes three categories of prosodic rules that create rhythmic successions that are additive (same duration repeated), cumulative (short-long), or countercumulative (long-short).