Rhythm means a "movement marked by the regulated succession of strong and weak elements, or of opposite or different conditions". 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. In the performance arts, rhythm is the timing of events on a human scale. In some performing arts, such as hip hop music, the rhythmic delivery of the lyrics is one of the most important elements of the style. Rhythm may refer to visual presentation, as "timed movement through space" and a common language of pattern unites rhythm with geometry. In recent years and meter have become an important area of research among music scholars. Recent work in these areas includes books by Maury Yeston, Fred Lerdahl and Ray Jackendoff, Jonathan Kramer, Christopher Hasty, Godfried Toussaint, William Rothstein, Joel Lester, Guerino Mazzola. In his television series How Music Works, Howard Goodall presents theories that human rhythm recalls the regularity with which we walk and the heartbeat.
Other research suggests that it does not relate to the heartbeat directly, but rather the speed of emotional affect, which influences 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". Justin London writes that musical metre "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"; 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". Joseph Jordania suggested that the sense of rhythm was developed in the early stages of hominid evolution by the forces of natural selection. Plenty of animals walk rhythmically and hear the sounds of the heartbeat in the womb, but only humans have the ability to be engaged in rhythmically coordinated vocalizations and other activities.
According to Jordania, development of the sense of rhythm was central for the achievement of the specific neurological state of the battle trance, crucial for the development of the effective defense system of early hominids. Rhythmic war cry, rhythmic drumming by shamans, rhythmic drilling of the soldiers and contemporary professional combat forces listening to the heavy rhythmic rock music all use the ability of rhythm to unite human individuals into a shared collective identity where group members put the interests of the group above their individual interests and safety; some types of parrots can know rhythm. Neurologist Oliver Sacks states that chimpanzees and other animals show no similar appreciation of rhythm yet posits that human affinity for rhythm is fundamental, so that a person's sense of rhythm cannot be lost. "There is not a single report of an animal being trained to tap, peck, or move in synchrony with an auditory beat" Human rhythmic arts are to some extent rooted in courtship ritual.
The establishment of a basic beat requires the perception of a regular sequence of distinct short-duration pulses and, as a subjective perception of loudness is relative to background noise levels, a pulse must decay to silence before the next occurs if it is to be distinct. For this reason, the fast-transient sounds of percussion instruments lend themselves to the definition of rhythm. Musical cultures that rely upon such instruments may develop multi-layered polyrhythm and simultaneous rhythms in more than one time signature, called polymeter; such are the cross-rhythms of Sub-Saharan Africa and the interlocking kotekan rhythms of the gamelan. For information on rhythm in Indian music see Tala. For other Asian approaches to rhythm see Rhythm in Persian music, Rhythm in Arabian music and Usul—Rhythm in Turkish music and Dumbek rhythms. Most music and oral poetry establishes and maintains an underlying "metric level", a basic unit of time that may be audible or implied, the pulse or tactus of the mensural level, or beat level, sometimes called the beat.
This consists of a series of identical yet distinct periodic short-duration stimuli perceived as points in time. The "beat" pulse is not the fastest or the slowest component of the rhythm but the one, perceived as fundamental: it has a tempo to which listeners entrain as they tap their foot or dance to a piece of music, it is most designated as a crotchet or quarter note in western notation. Faster levels are division levels, slower levels are mul
Vowel harmony is a type of long-distance assimilatory phonological process involving vowels that occurs in some languages. A vowel or vowels in a word must be members of the same class. In languages with vowel harmony, there are constraints. Suffixes and prefixes will follow vowel harmony rules. Many agglutinative languages have vowel harmony; the term vowel harmony is used in two different senses. In the first sense, it refers to any type of long distance assimilatory process of vowels, either progressive or regressive; when used in this sense, the term vowel harmony is synonymous with the term metaphony. In the second sense, vowel harmony refers only to progressive vowel harmony. For regressive harmony, the term umlaut is used. In this sense, metaphony is the general term while vowel harmony and umlaut are both sub-types of metaphony; the term umlaut is used in a different sense to refer to a type of vowel gradation. This article will use "vowel harmony" for both regressive harmony. Harmony processes are "long-distance" in the sense that the assimilation involves sounds that are separated by intervening segments.
In other words, harmony refers to the assimilation of sounds. For example, a vowel at the beginning of a word can trigger assimilation in a vowel at the end of a word; the assimilation occurs across the entire word in many languages. This is represented schematically in the following diagram: In the diagram above, the Va causes the following Vb to assimilate and become the same type of vowel; the vowel that causes the vowel assimilation is termed the trigger while the vowels that assimilate are termed targets. When the vowel triggers lie within the root or stem of a word and the affixes contain the targets, this is called stem-controlled vowel harmony; this is common among languages with vowel harmony and may be seen in the Hungarian dative suffix: The dative suffix has two different forms -nak/-nek. The -nak form appears after the root with back vowels; the -nek form appears after the root with front vowels. Vowel harmony involves dimensions such as Nasalization In many languages, vowels can be said to belong to particular sets or classes, such as back vowels or rounded vowels.
Some languages have more than one system of harmony. For instance, Altaic languages are proposed to have a rounding harmony superimposed over a backness harmony. Among languages with vowel harmony, not all vowels need to participate in the vowel conversions. Neutral vowels may be opaque and block harmonic processes or they may be transparent and not affect them. Intervening consonants are often transparent. Languages that do have vowel harmony allow for lexical disharmony, or words with mixed sets of vowels when an opaque neutral vowel is not involved. Point to two such situations: polysyllabic trigger morphemes may contain non-neutral vowels from opposite harmonic sets and certain target morphemes fail to harmonize. Many loanwords exhibit disharmony. For example, Turkish vakit,. There are three classes of vowels in Korean: positive and neutral; these categories loosely follow mid vowels. Traditionally, Korean had strong vowel harmony. In modern Korean, it is only applied in certain cases such as onomatopoeia, adverbs and interjections.
The vowel ㅡ is considered a neutral and a negative vowel. There are other traces of vowel harmony in modern Korean: many native Korean words tend to follow vowel harmony such as 사람, 부엌. Mongolian exhibits a rounding harmony. In particular, the pharyngeal harmony involves the vowels: /a, ʊ, ɔ/ and /i, u, e, o/. Rounding harmony only affects the open vowels, /e, o, a, ɔ/. Turkic languages inherit their systems of vowel harmony from Proto-Turkic, which had a developed system. Azerbaijani's system of vowel harmony has rounded/unrounded vowels. Tatar has no neutral vowels; the vowel é is found only in loanwords. Other vowels could be found in loanwords, but they are seen as Back vowels. Tatar language has a rounding harmony, but it is not represented in writing. O and ö could be written only in the first syllable, but vowels they mark could be pronounced in the place where ı and e are written. Kazakh's system of vowel harmony is a front/back system, but there is a system of rounding harmony, not represented by the orthography, which resembles the system in Kyrgyz.
Kyrgyz's system of vowel harmony is a front/back system, but there is a system of rounding harmony, which resembles that of Kazakh. Turkish has a 2-dimensional vowel harmony system, where vowels are characterised by two features: and. There are two sets of vocal harmony systems: a complex one; the simple one is concerned with the low vowels e, a and has only the feature. The complex one has both and features; the close-mid vowels ö, o are not involved