Polyphony

Polyphony is a type of musical texture consisting of two or more simultaneous lines of independent melody, as opposed to a musical texture with just one voice, monophony, or a texture with one dominant melodic voice accompanied by chords, homophony.
Within the context of the Western musical tradition, the term "polyphony" is usually used to refer to music of the late Middle Ages and Renaissance. Baroque forms such as fugue, which might be called polyphonic, are usually described instead as contrapuntal. Also, as opposed to the "species" terminology of counterpoint, polyphony was generally either "pitch-against-pitch" / "point-against-point" or "sustained-pitch" in one part with melismas of varying lengths in another. In all cases the conception was probably what Margaret Bent (1999) calls "dyadic counterpoint", with each part being written generally against one other part, with all parts modified if needed in the end. This point-against-point conception is opposed to "successive composition", where voices were written in an order with each new voice fitting into the whole so far constructed, which was previously assumed.
The term "polyphony" is also sometimes used more broadly, to describe any musical texture that is not monophonic. Such a perspective considers homophony as a sub-type of polyphony.
Origins.
Traditional (non-professional) polyphony has a wide, if uneven, distribution among the peoples of the world. Most polyphonic regions of the world are in sub-Saharan Africa, Europe and Oceania. It is believed that the origins of polyphony in traditional music vastly predate the emergence of polyphony in European professional music. Currently there are two contradictory approaches to the problem of the origins of vocal polyphony: the Cultural Model, and the Evolutionary Model. According to the Cultural Model, the origins of polyphony are connected to the development of human musical culture; polyphony came as the natural development of the primordial monophonic singing; therefore polyphonic traditions are bound to gradually replace monophonic traditions. According to the Evolutionary Model, the origins of polyphonic singing are much deeper, and are connected to the earlier stages of human evolution; polyphony was an important part of a defence system of the hominids, and traditions of polyphony are gradually disappearing all over the world.
Although the exact origins of polyphony in the Western church traditions are unknown, the treatises "Musica enchiriadis" and "Scolica enchiriadis", both dating from "c". 900, are usually considered the oldest extant written examples of polyphony. These treatises provided examples of two-voice note-against-note embellishments of chants using parallel octaves, fifths, and fourths. Rather than being fixed works, they indicated ways of improvising polyphony during performance. The "Winchester Troper", from "c". 1000, is the oldest extant example of notated polyphony for chant performance, although the notation does not indicate precise pitch levels or durations.
European polyphony.
Historical context.
European polyphony rose out of melismatic organum, the earliest harmonization of the chant. Twelfth-century composers, such as Léonin and Pérotin developed the organum that was introduced centuries earlier, and also added a third and fourth voice to the now homophonic chant. In the thirteenth century, the chant-based tenor was becoming altered, fragmented, and hidden beneath secular tunes, obscuring the sacred texts as composers continued to play with this new invention called polyphony. The lyrics of love poems might be sung above sacred texts in the form of a trope, or the sacred text might be placed within a familiar secular melody. The oldest surviving piece of six-part music is the English rota "Sumer is icumen in" (c. 1240).
These musical innovations appeared in a greater context of societal change. After the first millennium, European monks decided to start translating the works of Greek philosophers into the vernacular. Western Europeans were aware of Plato, Socrates, and Hippocrates during the Middle Ages. However they had largely lost touch with the content of their surviving works because the use of Greek as a living language was restricted to the lands of the Eastern Roman Empire (Byzantium). Once these ancient works started being translated thus becoming accessible, the philosophies had a great impact on the mind of Western Europe. This sparked a number of innovations in medicine, science, art, and music.
Western Europe and Roman Catholicism.
European polyphony rose prior to, and during the period of the Western Schism. Avignon, the seat of the antipopes, was a vigorous center of secular music-making, much of which influenced sacred polyphony.
It was not merely polyphony that offended the medieval ears, but the notion of secular music merging with the sacred and making its way into the papal court. It gave church music more of a jocular performance quality removing the solemn worship they were accustomed to. The use of and attitude toward polyphony varied widely in the Avignon court from the beginning to the end of its religious importance in the fourteenth century. Harmony was not only considered frivolous, impious, and lascivious, but an obstruction to the audibility of the words. Instruments, as well as certain modes, were actually forbidden in the church because of their association with secular music and pagan rites. Dissonant clashes of notes give a creepy feeling that was labeled as evil, fueling their argument against polyphony as being the devil's music. After banishing polyphony from the Liturgy in 1322, Pope John XXII spoke in his 1324 bull "Docta Sanctorum Patrum" warning against the unbecoming elements of this musical innovation. Pope Clement VI, however, indulged in it.
The oldest extant polyphonic setting of the mass attributable to one composer is Guillaume de Machaut's Messe de Nostre Dame, dated to 1364, during the pontificate of Pope Urban V.
More recently, the Second Vatican Council (1962–1965) stated: "Gregorian chant, other things being equal, should be given pride of place in liturgical services. But other kinds of sacred music, especially polyphony, are by no means excluded... Religious singing by the people is to be skillfully fostered, so that in devotions and sacred exercises, as also during liturgical services, the voices of the faithful may ring out".
Protestant Britain and the United States.
English Protestant west gallery music included polyphonic multi-melodic harmony, including fuguing tunes, by the mid-18th century. This tradition passed with emigrants to North America, where it was proliferated in tunebooks, including shape-note books like "The Southern Harmony" and "The Sacred Harp". While this style of singing has largely disappeared from British and North American sacred music, it survived in the rural Southern United States, until it again began to grow a following throughout the United States and even in places such as Ireland, the United Kingdom, Poland, Australia and New Zealand, among others.
Balkan region.
Polyphonic singing in the Balkans is traditional folk singing of this part of southern Europe. It is also called "ancient", "archaic" or "old-style" singing.
Incipient polyphony (previously primitive polyphony) includes antiphony and call and response, drones, and parallel intervals.
Balkan drone music is described as polyphonic due to Balkan musicians using a literal translation of the Greek ('many voices'). In terms of Western classical music, it is not strictly polyphonic, due to the drone parts having no melodic role, and can better be described as "multipart".
The polyphonic singing tradition of Epirus is a form of traditional folk polyphony practiced among Aromanians, Albanians, Greeks, and ethnic Macedonians in southern Albania and northwestern Greece. This type of folk vocal tradition is also found in North Macedonia and Bulgaria.
Albanian polyphonic singing can be divided into two major stylistic groups as performed by the Tosks and Labs of southern Albania. The drone is performed in two ways: among the Tosks, it is always continuous and sung on the syllable 'e', using staggered breathing; while among the Labs, the drone is sometimes sung as a rhythmic tone, performed to the text of the song. It can be differentiated between two-, three- and four-voice polyphony.
The phenomenon of Albanian folk iso-polyphony (Albanian iso-polyphony) has been proclaimed by UNESCO a "Masterpiece of the Oral and Intangible Heritage of Humanity". The term "iso" refers to the drone, which accompanies the iso-polyphonic singing and is related to the ison of Byzantine church music, where the drone group accompanies the song.
Corsica.
The French island Corsica has a unique style of music called that is known for its polyphony. Traditionally, Paghjella contains a staggered entrance and continues with the three singers carrying independent melodies. This music tends to contain much melisma and is sung in a nasal temperament. Additionally, many paghjella songs contain a picardy third. After paghjella's revival in the 1970s, it mutated. In the 1980s it had moved away from some of its more traditional features as it became much more heavily produced and tailored towards western tastes. There were now four singers, significantly less melisma, it was much more structured, and it exemplified more homophony. To the people of Corsica, the polyphony of paghjella represented freedom; it had been a source of cultural pride in Corsica and many felt that this movement away from the polyphonic style meant a movement away from paghjella's cultural ties. This resulted in a transition in the 1990s. Paghjella again had a strong polyphonic style and a less structured meter.
Sardinia.
Cantu a tenore is a traditional style of polyphonic singing in Sardinia.
Caucasus region.
Georgia.
Polyphony in the Republic of Georgia is arguably the oldest polyphony in the Christian world. Georgian polyphony is traditionally sung in three parts with strong dissonances, parallel fifths, and a unique tuning system based on perfect fifths. Georgian polyphonic singing has been proclaimed by UNESCO an Intangible Cultural Heritage of Humanity. Polyphony plays a crucial role in Abkhazian traditional music. Polyphony is present in all genres where the social environment provides more than one singer to 
support the melodic line. The ethnomusicologist Izaly Zemtsovsky reported witnessing an example of such an incident, in which an Abkhazian dozing at a bus stop started singing a drone to support a singer unknown to him. Abkhazian two and three-part polyphony is based on a drone (sometimes a double drone). Two part drone songs are considered by Abkhazian and Georgian scholars the most important indigenous style of Abkhazian polyphony. Two-part drone songs are dominating in Gudauta district, the core region of ethnic Abkhazians. Millennia of cultural, social and economic interactions between Abkhazians and Georgians on this territory resulted in reciprocal influences, and in particular, creation of a new, so-called "Georgian style" of three-part singing in Abkhazia, unknown among Adyghes. This style is based on two leading melodic lines (performed by soloists - akhkizkhuo) singing together with the drone or ostinato base (argizra). Indigenous Abkhazian style of three-part polyphony uses double drones (in fourths, fifths, or octaves) and one leading melodic line at one time. Abkhazians use a very specific cadence: tetrachordal downward movement, ending on the interval of a fourth.
Chechens and Ingushes.
Both Chechen and Ingush traditional music could be very much defined by their 
tradition of vocal polyphony. As in other North Caucasian musical cultures, Chechen and 
Ingush polyphony is based on a drone. Unlike most of the other North Caucasian 
polyphonic traditions (where two-part polyphony is the leading type), Chechen and Ingush polyphony is mostly three-part. Middle part, the carrier of the main melody of 
songs, is accompanied by the double drone, holding the interval of the fifth "around" the 
main melody. Intervals and chords, used in Chechen and Ingush polyphony, are often 
dissonances (sevenths, seconds, fourths). This is quite usual in all North Caucasian 
traditions of polyphony as well, but in Chechen and Ingush traditional songs more sharp 
dissonances are used. In particular, a specific cadence, where the final chord is a 
dissonant three-part chord, consisting of fourth and the second on top (c-f-g), is quite 
unique for North Caucasia. Only on the other side of Caucasian mountains, in western
Georgia, there are only few songs that finish on the same dissonant chord (c-f-g).
Oceania.
Parts of Oceania maintain rich polyphonic traditions.
Melanesia.
The peoples of New Guinea Highlands including the Moni, Dani, and Yali use vocal polyphony, as do the people of Manus Island. Many of these styles are drone-based or feature close, secondal harmonies dissonant to western ears. Guadalcanal and the Solomon Islands are host to instrumental polyphony, in the form of bamboo panpipe ensembles.
Polynesia.
Early European encounters with Polynesians were surprised to find polyphonic singing there, which was likely drone-based and dissonant, like Melanesian polyphony. However, Polynesian traditions became strongly influenced by Western choral church music, which brought counterpoint into Polynesian musical practice.
Africa.
"See Also Traditional sub-Saharan African harmony"
Numerous Sub-Saharan African music traditions host polyphonic singing, typically moving in parallel motion.
East Africa.
While the Maasai people traditionally sing with drone polyphony, other East African groups use more elaborate techniques. The Dorze people, for example, sing with as many as six parts, and the Wagogo use counterpoint.
Central Africa.
The music of African Pygmies (e.g. that of the Aka people) is typically ostinato and contrapuntal, featuring yodeling. Other Central African peoples tend to sing with parallel lines rather than counterpoint.
Southern Africa.
The singing of the San people, like that of the pygmies, features melodic repetition, yodeling, and counterpoint. The singing of neighboring Bantu peoples, like the Zulu, is more typically parallel.
West Africa.
The peoples of tropical West Africa traditionally use parallel harmonies rather than counterpoint.