rhythm(redirected from atrioventricular (AV) junctional rhythm)
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rhythm,the basic temporal element of music, concerned with duration and with stresses or accents whether irregular or organized into regular patternings. The formulation in the late 12th cent. of the rhythmic modes—basic recurrent patterns that were adhered to in composition—began the development of the Western system of metermeter,
in music, the division of a composition into units of equal time value called measures, and the subdivision of those measures into an underlying pattern of stresses or accents (see measure).
..... Click the link for more information. and its notation. Most rhythms are metrical, i.e., the values are multiples of a temporal unit, or beat, usually associated with some particular note value. Free rhythm, such as occurs in much Asian music, has no meter (i.e., its temporal values are not derived from a basic unit). The degree of rhythmic complexity and the types of rhythms used are major considerations in analysis of the style of a composer or a period. The rhythmic tension of music is of value in eliciting emotional response from the hearer. African music and some 20th-century composers employ polyrhythm, the simultaneous use of several rhythmic patterns whose accents do not coincide. See syncopationsyncopation
[New Gr.,=cut off ], in music, the accentuation of a beat that normally would be weak according to the rhythmic division of the measure. Although the normally strong beat is not usually effaced by the process, there are occasions (e.g.
..... Click the link for more information. and metronomemetronome
, in music, originally pyramid-shaped clockwork mechanism to indicate the exact tempo in which a work is to be performed. It has a double pendulum whose pace can be altered by sliding the upper weight up or down.
..... Click the link for more information. .
See P. Kiparsky and G. Youmans, ed., Rhythm and Meter (1989).
the perceived form of the flow of processes in time; a basic principle of formal organization in the temporal arts, including poetry, music, and dance. The concept of rhythm is applicable to the spatial arts, to the extent that they presume a process of perception developing in time. The diversity with which rhythm is manifested in artistic genres and styles and outside of the arts (in speech and in work, for example) has given rise to many definitions and to a lack of terminological precision. The definitions of “rhythm” fall into three main groups: descriptive, rational, and emotional.
In the broadest sense, rhythm is the temporal structure of any perceived process—a structure formed by accents, pauses, divisions, groupings of segments, and correlation of segments by duration. Thus, the rhythm of speech consists of pronounced and heard accents and divisions that do not always coincide with semantic divisions, which are graphically expressed by punctuation marks and by spaces between words. In music, rhythm is distribution in time, or, more narrowly, the sequence of durations of sounds, dissociated from pitch (the rhythmic, as opposed to the melodic outline).
This descriptive approach is counterposed to the consideration of rhythm as a special quality that distinguishes rhythmic from non-rhythmic movement. However, there are contradictory definitions for this special quality. According to one of them, rhythm is an ordered sequence of repetition or a regularity based on sequence or repetition. From this standpoint, the repeated swings of a pendulum or the beats of a metronome represent the ideal of rhythm. The aesthetic impression received from such rhythmic movements is explained as “economy of attention,” which facilitates perception and promotes the automation of muscular work, as in walking, for example. In language, automation is manifested in a tendency to give equal duration to syllables or to the intervals between stresses. More frequently, rhythm in language is associated only with verse, with its specific, ordered sequence of stressed and unstressed or long and short syllables. Consequently, rhythm is identified with meter (in music, with the beat or the musical meter).
Rhythm is especially important in poetry and music, which are precisely the art forms in which rhythm is most often counterposed with meter and associated not with regular repetition but with a virtually inexplicable “vital feeling” that conveys an urgent, forward movement. In the article “How to Write Verses” V. V. Mayakovsky observed: “Rhythm is the basic force, the basic energy of verse. It is impossible to explain.” Unlike definitions of rhythm that focus on regularity (rationality) and persistent repetition (static quality), Mayakovsky’s statement emphasizes the emotional and dynamic character of rhythm, which can be manifested without meter in rhythmic prose and free verse and which can be absent in metrically correct verse.
The emotional (dynamic) and rational (static) viewpoints are not mutually exclusive. Rhythmic movements are perceived as evoking a resonance or sympathetic response that is expressed in an urge to reproduce the movements. Experiences of rhythm are directly associated with muscular sensations. External sensations are associated with sounds, the perception of which is often accompanied by inward, mental reproduction. A number of conditions are necessary for rhythmic experiences. The movement that is experienced as rhythmic is not chaotic but has a perceivable, repeatable structure. However, the repetition should not be mechanical. Rhythm is experienced as an alternation of emotional tensions and resolutions. This alternation disappears with precise, pendulum-like repetition. Rhythm combines static and dynamic elements. Since, however, the criterion of rhythmicity is emotional and is, therefore, largely subjective, it is impossible to establish the precise boundaries separating rhythmic from either chaotic or mechanical movements. For this reason, the descriptive approach, which serves as the foundation for many concrete studies of rhythm in language and music, is legitimate.
The alternation of tensions and resolutions (rising and falling phases) endows rhythmic structures with periodicity, which involves not only the repetition of a certain sequence of phases (similar to the concept of the period of oscillation) but also a “rounding off” that gives rise to repetition and a completeness that permits rhythm to be perceived even without repetition (the concept of the period in rhetoric and music). A rhythmic effect may be created by an entire composition, in which the development and dénouement are analogous to ascending and descending rhythmic phases. The division of a composition into sections (for example, by entr’actes in drama) may also have a rhythmic impact.
Rhythmic structure usually consists of segments that are smaller than compositional divisions and that are associated with physiological periodicities such as breathing and pulse, the prototypes of two kinds of rhythmic structure. Breathing is closer than pulse to the emotional sources of rhythm and further from mechanical repetition. Its periods, which are characterized by a clearly perceptible structure, are distinctly separated. The duration of each breath usually equals approximately four pulse beats, but it often diverges from this norm. In speech and music, breathing is the source of phrasing. It determines the size of the phrasing unit (the colon, or, as it is sometimes called in music, the rhythm) and creates pauses and a natural form of melodic cadence (literally, a “fall,” the descending phase of a rhythmic unit). The natural cadence is the result of the lowering of the voice at the end of an exhalation. The raising of the voice before a pause expresses a question or incomplete thought, making possible the formation of complex periods.
The alternation of melodic rising and falling (cadences) forms a “free, asymmetric rhythm,” with units of varying length. This is characteristic of Gregorian chant, as well as many folkloric forms, from primitive songs to Russian sustained singing. In this kind of melodic (intonational) rhythm, regularity arises from the addition of pulsational periodicity, which is manifested especially in songs associated with body movements (dance, game, and work songs). In pulsation, repetition prevails over the formal completion and separation of periods. The conclusion of one period is the impulse that begins a new period and establishes the beat, in relation to which the other unstressed moments appear to be secondary. They may be represented as pauses. Pulsational periodicity is characteristic of walking and regular work movements. In speech and music pulsational periodicity defines the tempo, or the duration of the intervals between beats. As a result of the intensification of the motor element, pulsation divides primary rhythmic intonational units associated with breathing into equal segments. This division strengthens motor reactions during perception and, consequently, intensifies the experience of rhythm.
Even during the early stages of the development of folk music, sustained singing was juxtaposed with “quick” songs, which had a greater rhythmic impact. The distinction between rhythm and melody was known in antiquity. Dances and music performed on percussive or plucked instruments were considered pure expressions of rhythm. In modern times, marches and dance music are still considered to be primarily rhythmic, but the concept of rhythm is more often associated with pulse than with breathing. A one-sided exaggeration of pulsational periodicity leads to mechanical repetition and the substitution of regular, equal beats for the alternation of tensions and resolutions. Series of beats cannot be rhythmically perceived unless there are differences among them that permit them to be grouped.
Pulsation provides the foundation for a subjective evaluation of time. Consequently, it is the foundation for the “rational,” chronometric, or quantitative rhythmics that characterizes syncretic, nonfolk, professional art and that received its classic expression in antiquity. In professional art proportionality is a function not of physiological tendencies but of aesthetic demands. The equal length of units of time is a particular case of their proportionality. In addition, there are other “kinds of rhythm”—for example, 1:2 and 2:3 ratios between arsis and thesis (the rising and falling parts of a rhythmic unit). In quantitative rhythmics the proportions become very complex, creating an architecture in time.
Dance owes its importance less to its motor character than to its plastic character, which is visual. For psychophysiological reasons, vision demands intermittent movement, a sequence of pictures with specific durations. In antiquity the style of dance conformed to this description. Rhythm consisted in the alternation of poses (schemas) separated by “signs” or “points” (the Greek word semeion captures both of these meanings). In quantitative rhythm beats are not impulses but boundaries of segments of contrasting lengths, to which time-values are assigned. The perception of time approaches that of space, and the concept of rhythm, that of symmetry. The subordination of temporal relationships to specific formulas, which distinguishes dance from other kinds of movement, is transferred to genres not directly associated with the dance, including the epic, in which a verbal text is organized into pre-established verse formulas.
Owing to differences in syllable length, a verse text becomes a measure (meter) for rhythm, but only as a sequence of long and short syllables. The actual rhythm (flow) of the verse—its division into arses and theses, which determine an accentuation independent of word stresses—is associated with the musical aspect of syncretic art. Classical rhythmics is sometimes used as the basis for concepts of rhythm as proportion and measure, as well as for the concept of meter as a manifestation of rhythm in language. However, this concept of meter is incorrect even with reference to antiquity, when the free (nonmetric) speech rhythm of oratorical prose was known. Verses based entirely on verbal stresses in speech emerged in late antiquity and were called rhythms, to distinguish them from quantitative meters.
Rhythmic versification, which became fully developed in modern times, gave rise to accentual rhythm, a third type of rhythm, the others being intonational and quantitative. Accentual rhythm is used in poetry and in music, which differ from each other and from dance. The dynamic and emotional aspects of rhythm are emphasized in the new verse systems, which, unlike metric versification, have developed not from oral speech but from “artificial” or “book” prose. The length of verse lines is regulated not by temporal relationships but by accentual impulses. Freedom and variety of rhythm are valued more highly than “correctness” (subordination to the rules of versification). In recitation the verse pattern prescribed by the rules of versification interacts with the variety of stresses and divisions in the text. This variety, which is permitted within the metric pattern, plays a dominant role and, as the rhythm of the verse proper, usually works in opposition to the meter. Thus, in syllabotonic versification, in which the meter establishes the correct sequence of strong and weak syllables, rhythmic variety is achieved, under certain conditions, by permitting the absence of word stresses where they would otherwise be required by the metric stress, and by placing the stress on metrically weak syllables. Additional variety is achieved by the placement of word divisions, syntactic pauses, and phrasing accents.
A similar juxtaposition of rhythm and meter develops in music after it has become independent of verse. In music, meter represents an ideal pattern of alternating strong and weak accents, from which the actual accentuation may depart to a greater degree than in verse (syncopation). With this pattern as a background, rhythmic variety is created by musically meaningful accents and divisions, such as phrasing. (Musical meter, unlike verse meter, does not require division into lines. In this sense, music is closer to prose than to verse.) Other techniques for creating rhythmic variety in music include grouping beats (for example, Beethoven’s instructions calling for “three-beat” and “four-beat” rhythms), as well as filling a beat with notes of different values, thus establishing a rhythmic outline. (Many elementary textbooks in music theory reduce the concept of rhythm to the rhythmic outline of a piece.)
In contemporary accentual rhythmics the relationships between different note values have lost their independent significance and have become a means of accentuation, distinguishing longer from shorter sounds. Moreover, the designations of note values forming the rhythmic outline refer not to actual durations but to a share of the beat. In performance these shares are, within certain broad limits, freely prolonged or curtailed.
The tendency toward greater stability of temporal proportions in 20th-century music has led to the revival of certain features of quantitative rhythmics. Motion pictures and recordings, in which duration may be expressed spatially in terms of a certain length of film or tape, have reinforced the trend toward stable temporal proportions in contemporary music.
In the plastic arts rhythm is an important compositional resource for the creation of artistic works. It is also essential in the formation of images. A particular form of rhythmic organization may be used to impart a particular emotional overtone to a work of art. Rhythmic structures are achieved by means of various elements of symmetry and by the alternation or juxtaposition of compositional elements, such as contrasts or correspondences between masses, individual objects, lines, rendering of movements, areas of light and shadow or color, and spatial divisions. Rhythmic organization contributes to the creation of artistic images and to the clear perception of artworks by the viewer.
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Bücher, K. Rabota i ritm. Moscow, 1923. (Translated from German.)
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M. G. KHARLAP (rhythm in music and verse)