The handling of time in music is expressed through concepts such as the lengths of notes and the interrelationships among them; relative degrees of emphasis on different tones; and, in particular, meter.

Most Western music is built on a structure of regularly recurring beats-that is, a metrical structure. This structure may be explicit (as in the beating of the bass drum in popular music and marching bands), or it may be implied (often in symphonic or piano music). The three most common meters in Western music are units of four beats (with main stress on the first beat, secondary stress on the third beat); of three beats (stress on the first); and of six beats (primary stress on the first, secondary on the fourth). Conventionally, these meters are called o, k, and u. Far greater complexity is found, however, in 20th-century Western art music, Indian classical music, and West African drum ensembles. Furthermore, much music is structured without regular meter, as in some genres in India and the Middle East, and in Christian, Jewish, Islamic, and Buddhist liturgical chant.

Other Elements

The organization given to simultaneously produced pitches is also of great importance. Two or more voices or instruments performing together may be perceived as producing independent although related melodies (counterpoint); or the emphasis may be on how the groups of simultaneous tones (chords) are related to one another, as well as on the progression of such groups through time (harmony).

Timbre, or sound quality, is the musical element that accounts for the differences in the characteristic sounds of musical instruments. Singers have a variety of timbres as well, each affected by such features as vocal tension, rasp, nasality, amount of accentuation, and slurring of pitch from one tone to the next .

One major characteristic of music everywhere is its transposability. A tune can be performed at various pitch levels and will be recognized as long as the interval relationships among the tones remain constant. Analogously, rhythmic patterns can almost always be perceived as identical, whether executed quickly or slowly.

These elements of music are used to organize pieces extending from simple melodies using a scale of three tones and lasting only ten seconds (as in the simplest tribal musics) to highly complex works such as operas and symphonies. The organization of music normally involves the presentation of basic material that may then be repeated precisely or with changes (variations), may alternate with other materials, or may proceed continually to present new material. Composers in all societies, often unconsciously, strike a balance between unity and variety, and all pieces of music contain a certain amount of repetition-whether of individual tones, short groups of tones (motives), or longer units such as melodies or chord sequences (often called themes).
Instruments

All societies have vocal music; and with few exceptions, all have instruments. Among the simplest instruments are sticks that are struck together; notched sticks that are scraped; rattles; and body parts used to produce sound, as in slapping the thighs and clapping. Such simple instruments are found in many tribal cultures; elsewhere, they may be used as toys or in archaic rituals. Certain highly complex instruments exhibit flexibility not only in pitch but also in timbre. The piano produces the chromatic scale from the lowest to the highest pitch used in the Western system and responds, in quality of sound, to wide variation in touch. On the organ, each keyboard can be connected at will to a large number and combination of pipes, thereby making available a variety of tone colors. On the Indian sitar, one plucked string is used for melody, other plucked strings serve as drones, while still others produce fainter sounds through sympathetic vibration. Modern technology has utilized electronic principles to create a number of instruments that have almost infinite flexibility.
Instrument types are so numerous that classification systems have had to be developed. The most widely used system distinguishes (1) idiophones, in which the main vibrating units are the resonant bodies of the instruments themselves (for example, rattles and xylophones); (2) membranophones, which have vibrating skins (drums); (3) chordophones, which have vibrating strings (violins, guitars, pianos); (4) aerophones, which produce vibrating bodies of air (clarinets, reed and pipe organs, harmonicas); and (5) electrophones, in which electronic circuits produce sound (electronic organs, sound synthesizers).
 

The Creation of Music

Music is created by individuals, using a traditional vocabulary of musical elements. In composition-the principal creative act in music-something that is considered new is produced by combining the musical elements that a given society recognizes as a system. Innovation as a criterion of good composing is important in Western culture, less so in certain other societies. In Western music, composition is normally carried out with the help of notation; but in much popular music, and particularly in folk, tribal, and most non-Western cultures, composition is done in the mind of the composer, who may sing or use an instrument as an aid. Creative acts in music also include improvisation, or the creation of new music in the course of performance. Improvisation usually takes place on the basis of some previously determined structure, such as a tone or a group of chords; or it occurs within a set of traditional rules, as in the ragas of India or the maqams of the Middle East. Performance, which involves a musician's personal interpretation of a previously composed piece, has smaller scope for innovation. It may, however, be viewed as part of a continuum with composing and improvising.

The normal method of retaining music and transmitting it is oral or, more properly, aural- most of the world's music is learned by hearing. The complex system of musical notation used in Western music is in effect a graph, indicating principally movement in pitch and time, with only limited capability to regulate more subtle elements such as timbre. Both Western and Asian cultures possess other notation systems, giving letter names of notes, indicating hand positions, or charting the approximate contour of melodic movement.
 

The Social Role of Music

Music everywhere is used to accompany other activities. It is, for example, universally associated with dance. Although words are not found in singing everywhere, the association of music and poetry is so close that language and music are widely believed to have had a common origin in early human history.
 

The Function of Music

Music is a major component in religious services, secular rituals, theater, and entertainment of all sorts. In many societies it is also an activity carried on for its own sake. In American society in the late 20th century, for example, one main use of music involves listening at concerts or to radio or records (music for its own sake); another involves the provision of music as a suitable background for unrelated activities such as study or shopping (music as an adjunct to something else). In many societies music serves as the chief entertainment at royal courts. Everywhere, musicians sometimes perform for their own diversion; in some societies, however, this private use of music has been formalized-in southern Africa, for example, special genres and styles are reserved for musicians' performances for their personal entertainment.

The most ubiquitous use of music, however, is as a part of religious ritual. In some tribal societies, music appears to serve as a special form of communication with supernatural beings, and its prominent use in modern Christian and Jewish services may be a remnant of just such an original purpose. Another, less obvious, function of music is social integration. For most social groups, music can serve as a powerful symbol. Members of most societies share keen feelings as to what kind of music "belongs." Indeed, some minorities (including, in the U.S., black Americans and Euro-American ethnic groups) use music as a major symbol of group identity.