From Wikipedia, the free encyclopediaA 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 as a group 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 21st 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.
Structure of choirsChoirs 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 servicesEastern 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 functionIn 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.
 ContemporaryAlthough many contemporary churches have replaced the choir with singers, some churches have choirs which are backing vocalists in contrary to front line singers, which are in the Alto, Soprano and Tenor range for both Males and Females. Unlike traditional churches, these choir members clap along to the songs, raise hands and even dance on the pedestal in an act of encouraging the congregation to do likewise. Some of these choirs do not even have a conductor.
- 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, or Male Chorale, 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.
- Church choirs
- Collegiate and university choirs
- Community choirs (of children or adults)
- Professional choirs, either independent (e.g. Anúna) or state-supported (e.g., BBC Singers, National Chamber Choir of Ireland, Canadian Chamber Choir, Swedish Radio Choir).
- School choirs
- Signing choirs (of Deaf or Hearing individuals), using Sign Language rather than voices
- Integrated Signing and Singing Choirs, using both Sign Language and Voices and led by both a Signductor and a Musical Director.
- Bach choirs
- Barbershop music
- Gospel choirs
- Show choirs, in which the members sing and dance, often in performances somewhat like musicals
- Symphonic choirs
- Vocal jazz choirs
 Arrangements on stage
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
| ||This section does not cite any references or sources.|
Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (July 2008)
- 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 of proper vocal technique;
- to sing using pure vowels through vowel tracking to match the group;
- 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