A choir, chorale, or chorus is a musical ensemble of singers. Choral music, in turn, is the music written specifically for such an ensemble to perform.

A body of singers who perform together is called a choir or chorus. The former term is very often applied to groups affiliated with a church (whether or not they actually occupy the choir) and the second to groups that perform in theatres or concert halls, but this distinction is far from rigid. The term "Choir" has the secondary definition of a subset of an ensemble; thus one speaks of the "woodwind choir" of an orchestra, or different "choirs" of voices and/or instruments in a polychoral composition. In typical 18th to 20th century oratorios and masses, chorus or choir is usually understood to imply more than one singer per part, in contrast to the quartet of soloists also featured in these works.
thumb|350px| [[Evensong in the quire of the York Minster, showing carved choirstalls. ]]

Structure of choirs

Choirs are often led by a conductor or choirmaster. Most often choirs consist of four sections intended to sing in four part harmony, but there is no limit to the number of possible parts as long as there is a singer available to sing the part: Thomas Tallis wrote a 40-part motet entitled Spem in alium, for eight choirs of five parts each; Krzysztof Penderecki's Stabat Mater is for three choirs of 16 voices each, a total of 48 parts. Other than four, the most common number of parts are three, five, six and eight.

Choirs can sing with or without instrumental accompaniment. Singing without accompaniment is called a cappella singing (although the American Choral Directors Association discourages this usage in favor of "unaccompanied", since a cappella denotes singing "as in the chapel" and much unaccompanied music today is secular). Accompanying instruments vary widely, from only one to a full orchestra; for rehearsals a piano or organ accompaniment is often used, even if a different instrumentation is planned for performance, or if the choir is rehearsing unaccompanied music.

In Worship Services

Accompaniment

Eastern Orthodox churches, some American protestant groups, and some synagogues do not use instruments. In churches of the Western Rite the accompanying instrument is usually the organ, although in colonial America, the Moravian Church used groups of strings and winds. Many churches which use a contemporary worship format use a small amplified band to accompany the singing, and Roman Catholic Churches may use, at their discretion, additional orchestral accompaniment.

Liturgical Function

In addition to leading of singing in which the congregation participates, such as hymns and service music, some church choirs still sing full liturgies, including propers (introit, gradual, communion antiphons appropriate for the different times of the liturgical year). Chief among these are the Anglican and Roman Catholic churches; far more common however is the performance of anthems or motets at designated times in the service.

Types of Choirs

• Mixed choirs (with male and female voices). This is perhaps the most common type, usually consisting of soprano, alto, tenor and bass voices, often abbreviated as SATB. Often one or more voices is divided into two, e.g., SSAATTBB, where each voice is divided into two parts, and SATBSATB, where the choir is divided into two semi-independent four-part choirs. Occasionally baritone voice is also used (e.g., SATBarB), often sung by the higher basses. In smaller choirs with fewer men, SAB, or Soprano, Alto, and Baritone arrangements allow the few men to share the role of both the tenor and bass in a single part.

• Male choirs, with the same SATB voicing as mixed choirs, but with boys singing the upper part (often called trebles or boy sopranos) and men singing alto (in falsetto), also known as countertenors. This format is typical of the British cathedral choir.

• Female choirs, usually consisting of soprano and alto voices, two parts in each, often abbreviated as SSAA, or as soprano I, soprano II, and alto, abbreviated SSA.

• Men's choirs, usually consisting of two tenors, baritone, and bass, often abbreviated as TTBB (or ATBB if the upper part sings falsetto in alto range. ATBB may be seen in some barbershop quartet music.

• Children's choirs, often two-part SA or three-part SSA, sometimes more voices. This includes boychoirs.

Choirs are also categorized by the institutions in which they operate:

• Church choirs

• Collegiate and university choirs

• School choirs

• Community choirs (of children or adults)

• Signing choirs (of Deaf or Hearing individuals)- using Sign Language rather than voices

• Professional choirs, either independent (e.g.Philippine Madrigal Singers, Anúna) or state-supported (e.g., BBC Singers, National Chamber Choir of Ireland, Canadian Chamber Choir, Swedish Radio Choir).

Some choirs are categorized by the type of music they perform, such as

• Symphonic choirs

• Vocal jazz choirs

• Show choirs, in which the members sing and dance, often in performances somewhat like musicals

• African-American gospel choirs

Arrangements on Stage

There are various schools of thought regarding how the various sections should be arranged on stage. In symphonic choirs it is common (though by no means universal) to order the choir behind the orchestra from highest to lowest voices from left to right, corresponding to the typical string layout. Since 2000 several choirs introduced the historic layout of the 17th –19th century with the choir in front of the orchestra, so the American North Penn High School Concert Choir , the Canadian Tafelmusik Chamber Choir, the German Kreuznacher-Diakonie-Kantorei and the French Chapelle Rhénane. In a cappella or piano-accompanied situations it is not unusual for the men to be in the back and the women in front; some conductors prefer to place the basses behind the sopranos, arguing that the outer voices need to tune to each other.

More experienced choirs often sing with the voices all mixed together. Proponents of this method argue that it makes it easier for each individual singer to hear and tune to the other parts, but it requires more independence from each singer. Opponents argue that this method loses the spatial separation of individual voice lines, an otherwise valuable feature for the audience, and that it eliminates sectional resonance, which lessens the effective volume of the chorus.

For music with double (or multiple) choirs, usually the members of each choir are together, sometimes significantly separated, especially in performances of 16th-century music. Some composers actually specify that choirs should be separated, such as in Benjamin Britten's War Requiem.

Consideration is also given to the spacing of the singers. Studies have found that not only the actual formation, but the amount of space (both laterally and circumambiently) affect the perception of sound by choristers and auditors.

Skills involved in choral singing

Choral singers vary greatly in their ability and performance. The best choral singers possess (among others) the following abilities:

• to sing precisely in tune (on the correct pitch) and with a vocal timbre (or color) which complements the other singers;

• to sing at precisely controlled levels of volume, matching the dynamics marked in the score or prescribed by the conductor, and not sing so loudly as to be markedly detectable as an individual voice within the section;

• to sight-read music fluently;

• to read and pronounce the text accurately and in the pronunciation style specified by the leader, whatever the language may be. This includes correct diction, proper vowels and timing of diphthongs, and correct placement of consonants;

• to understand and interpret the music and to reflect that understanding in the vocal production of the music;

• to remain completely alert for long periods, monitoring closely what is going on in a rehearsal or performance;

• to monitor one's own singing and detect errors, correcting them as they go along,

• to accept direction from others for the good of the group as a whole, even when the singer disagrees aesthetically with the instructions;

• to produce a healthy and pleasing tone through the use proper vocal technique;

• to sing using pure vowels through vowel tracking to match the group;

Singers who have perfect pitch require yet other skills:

• to sing music in keys other than that in which it is written, since choirs often sing music in transposed form.

• to stay "in tune" with the ensemble, even in the event the ensemble modulates slightly away from "perfect" pitch

• to provide ensembles with the key or starting pitch that a piece begins on, usually with unaccompanied pieces

Historical overview of choral music

Antiquity

thumb|300px|Relief, now in [[National Archaeological Museum of Athens| Athens, showing Dionysus with actresses (possibly from The Bacchae) carrying masks and drums.]]

The oldest unambiguously choral repertory that survives is that of ancient Greece, of which the 2c BC Delphic hymns and the 2c A.D. hymns of Mesomedes are the most complete. The original Greek chorus sang its part in Greek drama, and fragments of works by Euripides (Orestes) and Sophocles (Ajax) are known from papyri. The Seikilos epitaph (2c BC) is a complete song (although possibly for solo voice). One of the latest examples, Oxyrhynchus hymn (3c) is also of interest as the earliest Christian music.

Of the Roman drama's music a single line of Terence surfaced in the 18c.

Medieval music

The earliest notated music of western Europe is Gregorian Chant, along with a few other types of chant which were later subsumed (or sometimes suppressed) by the Catholic Church. This tradition of unison choir singing lasted from sometime between the times of St. Ambrose (4th century) and Gregory the Great (6th century) up to the present. During the later Middle Ages, a new type of singing involving multiple melodic parts, called organum, became predominant for certain functions, but initially this polyphony was only sung by soloists. Further developments of this technique included clausulae, conductus and the motet (most notably the isorhythmic motet), which, unlike the Renaissance motet, describes a composition with different texts sung simultaneously in different voices. The first evidence of polyphony with more than one singer per part comes in the Old Hall Manuscript (1420, though containing music from the late 1300s), in which there are apparent divisi, one part dividing into two simultaneously sounding notes.

Renaissance music

During the Renaissance, sacred choral music was the principal type of formally-notated music in Western Europe. Throughout the era, hundreds of masses and motets (as well as various other forms) were composed for a cappella choir, though there is some dispute over the role of instruments during certain periods and in certain areas. Some of the better-known composers of this time include Dufay, Josquin des Prez, Giovanni Pierluigi da Palestrina, and William Byrd; the glories of Renaissance polyphony were choral, sung by choirs of great skill and distinction all over Europe. Choral music from this period continues to be popular with many choirs throughout the world today.

The madrigal, a partsong conceived for amateurs to sing in a chamber setting, originated at this period. Although madrigals were initially dramatic settings of unrequited-love poetry or mythological stories in Italy, they were imported into England and merged with the more dancelike balletto, celebrating carefree songs of the seasons, or eating and drinking. To most English speakers, the word madrigal now refers to the latter, rather than to madrigals proper, which refers to a poetic form of lines consisting of seven and eleven syllables each.

The interaction of sung voices in Renaissance polyphony influenced Western music for centuries. Composers are routinely trained in the "Palestrina style" to this day, especially as codified by the 18c music theorist Johann Joseph Fux. Composers of the early twentieth century also wrote in Renaissance-inspired styles. Herbert Howells wrote a Mass in the Dorian mode entirely in strict Renaissance style, and Ralph Vaughan Williams's Mass in G minor is an extension of this style. Anton von Webern wrote his dissertation on the Choralis Constantinus of Heinrich Isaac and the contrapuntal techniques of his serial music may be informed by this study.

Baroque music

The Baroque period in music is associated with the development around 1600 of the figured bass, with dramatic implications in the realm of solo vocal music such as the monodies of the Florentine Camerata and opera. This innovation was in fact an extension of established practice of accompanying choral music at the organ, either from a skeletal reduced score (from which otherwise lost pieces can sometimes be reconstructed) or from a basso seguente, a part on a single staff containing the lowest sounding part.

A new genre was the vocal concertato, combining voices and instruments; its origins may be sought in the polychoral music of the Venetian school.
Claudio Monteverdi (1567-1643) brought it to perfection with his Vespers and his Eighth Book of Madrigals, which call for great virtuosity on the part of singers and instruments alike. His pupil Heinrich Schütz (1585-1672) (who had earlier studied with Giovanni Gabrieli) introduced the new style to Germany. Alongside the new music of the secunda pratica, contrapuntal motets in the stile antico or old style continued to be written well into the 19th century.

It should be remembered that choirs at this time were usually quite small and that singers could be classified as suited to church or to chamber singing. Monteverdi, himself a singer, is documented as taking part in performances of his Magnificat with one voice per part.

Independent instrumental accompaniment opened up new possibilities for choral music. Verse anthems alternated accompanied solos with choral sections; the best-known composers of this genre were Orlando Gibbons and Henry Purcell. Grand motets (such as those of Lully and Delalande) separated these sections into separate movements. Oratorio, pioneered by Giacomo Carissimi, extended this concept into concert-length works, usually loosely based on Biblical stories.

The pinnacle of the oratorio is found in George Frideric Handel's works, notably Messiah and Israel in Egypt. While the modern chorus of hundreds had to await the growth of Choral societies and his centennial commemoration concert, we find Handel already using a variety of performing forces, from the soloists of the Chandos Anthems to larger groups (whose proportions are still quite different from modern orchestra choruses):

Lutheran composers wrote instrumentally-accompanied cantatas, often based on chorales (hymns). While Dieterich Buxtehude was a significant composer of such works, it was largely up to the next generation to undertake cantata cycles on texts for the entire church year. Telemann wrote choral cantatas for Frankfurt (later published in solo versions as the Harmonische Gottesdienst) and Graupner cycles for Darmstadt, but Johann Sebastian Bach (1685-1750) made a truly monumental contribution: his obituary mentions five complete cycles, of which three comprising some 200 works are known today, in addition to motets, (Bach himself did not use the term "cantata", motet here refers to his "church music" without orchestra) passions, masses and the Magnificat.
A point of hot controversy today is the so-called "Rifkin hypothesis", which re-examines the famous "Entwurff", Bach's 1730 memo to the Leipzig City Council (A Short but Most Necessary Draft for a Well Appointed Church Music) calling for at least 12 singers. In light of Bach's responsibility to provide music to four churches and be able to perform double choir compositions with a substitute for each voice, Joshua Rifkin concludes that Bach's music was normally written with one voice per part in mind. A few sets of original performing parts include ripieni who reinforce rather than slavishly double the vocal quartet.

Classical and Romantic music

Composers of the late 18th century became fascinated with the new possibilities of the symphony and other instrumental music, and generally neglected choral music. Mozart's choral music generally does not represent his best work, with a few exceptions (such as the "Great" Mass in C minor and Requiem in D minor). Haydn became more interested in choral music near the end of his life following his visits to England in the 1790s, when he heard various Handel oratorios performed by large forces; he wrote a series of masses beginning in 1797 and his two great oratorios The Creation and The Seasons. Beethoven wrote only two masses, both intended for liturgical use, although his Missa solemnis is suitable only for the grandest ceremonies. He also pioneered the use of chorus as part of symphonic texture with his Ninth Symphony.

In the 19th century, sacred music escaped from the church and leaped onto the concert stage, with large sacred works unsuitable for church use, such as Berlioz's Te Deum and Requiem, and Brahms's Ein deutsches Requiem. Rossini's Stabat mater, Schubert's masses, and Verdi's Requiem also exploited the grandeur offered by instrumental accompaniment.

Oratorios also continued to be written, clearly influenced by Handel's models. Berlioz's L'Enfance du Christ and Mendelssohn's Elijah and St Paul are in the category. Schubert, Mendelssohn, and Brahms also wrote secular cantatas, the best known of which are Brahms's Schicksalslied and Nänie.

A few composers developed a cappella music, especially Bruckner, whose masses and motets startlingly juxtapose Renaissance counterpoint with chromatic harmony. Mendelssohn and Brahms also wrote significant a cappella motets.

The amateur chorus (beginning chiefly as a social outlet) began to receive serious consideration as a compositional venue for the part-songs of Schubert, Schumann, Mendelssohn, Brahms, and others. These 'singing clubs' were often for women or men separately, and the music was typically in four-part (hence the name "part-song") and either a cappella or with simple instrumentation. At the same time, the Cecilian movement attempted a restoration of the pure Renaissance style in Catholic churches.

20th and 21st centuries

As in other genres of music, choral music underwent a period of experimentation and development during the 20th century. While few well-known composers focused primarily on choral music, most significant composers of the early century produced some fine examples that have entered the repertoire.

The late-Romantic composers, such as Richard Strauss and Sergei Rachmaninoff, contributed to the genre. Ralph Vaughan Williams's Mass in G minor harks back to the Renaissance style while exhibiting the vibrancy of new harmonic languages. Vaughan Williams also arranged English and Scottish folk songs. Arnold Schoenberg's Friede auf Erden is a tonal kaleidoscope, whose tonal centers are constantly shifting (his harmonically innovative Verklärte Nacht for strings dates from the same period).

The advent of atonality and other non-traditional harmonic systems and techniques in the 20th century also affected choral music. Serial music is represented by choral works by Arnold Schoenberg, including the anthem "Dreimal Tausend Jahre", while the composer's signature use of sprechstimme is evident in his psalm "De Profundis." Paul Hindemith's distinctive modal language is represented by both his a cappella Mass and his Six Chansons on texts by Rilke, while a more contrapuntally dissonant style comes through in his secular requiem, When Lilacs Last in the Dooryard Bloom'd. Olivier Messiaen also demonstrates dissonant counterpoint in his Cinq Rechants, which tell the Tristan and Isolde story. Charles Ives' psalm settings exemplify the composer's incomparably radical harmonic language. Tone clusters and aleatory elements play a prominent role in the choral music of Krzysztof Penderecki, who wrote the St. Luke Passio, and György Ligeti, who wrote both a Requiem and a separate Lux Aeterna. Milton Babbitt incorporated integral serialism into works for children's chorus, while Daniel Pinkham wrote for choir and electronic tape. Meredith Monk's Panda Chant and Astronaut Anthem explore overtones in an unconventional text setting. Though difficult and rarely performed by amateurs, pieces that demonstrate such unfamiliar idioms have found their way into the repertories of the finest semi-professional and professional choirs around the world.

More accessible styles of choral music include that by Benjamin Britten, including his War Requiem, Five Flower Songs, and Rejoice in the Lamb. Francis Poulenc's Motets pour le temps de noël, Gloria, and Mass in G are often performed. A primitivist approach is exemplified by Carl Orff's widely performed Carmina Burana. In the United States, Aaron Copland, Samuel Barber, and Randall Thompson wrote signature American pieces. In Eastern Europe, Béla Bartók and Zoltán Kodály wrote a small amount of music for choirs. Frank Martin's Mass for double choir combines modality and allusion to Medieval and Renaissance forms with a distinctly modern harmonic language and has become the composer's most performed work.

The so-called holy minimalists are represented by Arvo Pärt, whose Johannespassion and Magnificat have received regular performances; John Tavener (Song for Athene) and Henryk Gorecki (Totus Tuus) share this label. American minimalism and post minimalism are represented by Steve Reich's Desert Music, choral excerpts from Philip Glass's Einstein on the Beach and John Adams' The Death of Klinghoffer, and David Lang's Pulitzer Prize-winning Little Match Girl Passion.

At the turn of the 21st century, choral music has received a resurgence of interest partly due to a renewed interest in accessible choral idioms. Multi-cultural influences are found in Osvaldo Golijov's St. Mark Passion, which melds the Bach-style passion form with Latin American street music, and Chen Yi's Chinese Myths Cantata melds atonal idioms with traditional Chinese melodies played on traditional Chinese instruments. Some composers began to earn their reputation based first and foremost on their choral output, with the highly popular John Rutter being the most well-known example. The large scale dramatic works of Karl Jenkins seem to hearken back to the theatricality of Orff, and the music of James MacMillan continues the tradition of boundary-pushing choral works from the United Kingdom begun by Britten, Walton, and Leighton. Meanwhile, primarily media music composers such as John Williams and Kentaro Sato, and prominent concert orchestral composers such as Augusta Read Thomas, Sofia Gubaidulina, Aaron Jay Kernis, and Thomas Ades also contribute vital additions to the choral repertoire.

A number of traditions originating outside of classical concert music have enriched the choral repertoire as well as provided new outlets to composers:

• At the end of the 19th century and the start of the twentieth, male voice choirs became popular with the coal miners of South Wales, and numerous choirs were established including the Treorchy Male Choir, Morriston Orpheus Choir and Cor Meibion Pontypridd Male voice choirs. Although the mining communities which gave rise to these choirs largely died out in the 1970s and 1980s with the decline of the Welsh coal industry, many of these choirs continue, and are seen as a traditional part of Welsh culture and perform Worldwide. Not all male choirs were based around coal - some choirs started in the rugby clubs, such as Cardiff Arms Park Male Choir and Morriston Rugby Choir, while others such as Pontarddulais Male Choir were formed out of a youth choir.

• Black Spirituals entered the concert repertoire with the tours of the Fisk College Jubilee Singers, and arrangements of such spirituals are now part of the standard choral repertoire. Notable composers and arrangers of choral music in this tradition include William Dawson, Jester Hairston and Moses Hogan.

• During the mid 20th century, barbershop quartets began experimenting with combining larger ensembles together into choruses which sing barbershop music in 4 parts, often with staging, choreography and costumes. The first international barbershop chorus contest was held in 1953 and continues to this day.

• During the late 20th century, one of the major areas of growth in the choral movement has been in the areas of LGBT choruses. Starting around 1979, gay men's choruses were founded within a period of months in major U.S. cities such as New York, Los Angeles, Seattle and Dallas. Over the last quarter century the number of such groups, men's, women's and mixed, has exploded. GALA Choruses, an associative group, now has well-over 100 member choruses throughout the world.

See also

• :Category:Choirs

• Come and sing