What Is a Choir? Many Voices Trying to Sound Like One

The conventional division is by vocal range into soprano, alto, tenor and bass, which produces four-part harmony and is the default because it maps onto the four-voice writing that European church music settled into. The parts are not equal in function: the soprano usually carries the melody and is most exposed, the bass supplies the harmonic foundation and determines how a chord is heard, and the inner parts fill and connect, which is why alto and tenor lines are frequently less interesting to sing and are what holds the texture together. A choir may be mixed, or of equal voices, meaning all female or all male, and a great deal of repertoire exists for each. Section balance is a constant problem, since tenors are always in short supply and a top line of many bright voices will dominate unless the conductor works against it. Numbers range from a chamber choir of a dozen or fewer, where individual voices are audible and blend depends on precision, to a symphony chorus of two hundred, where blend happens automatically and precision is the difficulty.

Making many people sound like one instrument depends on a set of specific and teachable behaviours:

• •Unified vowels, since vowel shape determines timbre and a section singing an identical word with five different vowel colours will never blend, which is why choral rehearsal spends so much time on how a vowel is formed
• •Matched consonants, particularly the timing of the final one, because ragged endings are the most audible failure in amateur singing
• •Straight tone or restrained vibrato in much repertoire, since wide vibrato from many singers produces a wash rather than a chord
• •Listening outward rather than to oneself, which is the single instruction most often repeated and the hardest to follow
• •Breathing arranged so that not everyone breathes at once, called staggered breathing, which allows a line to continue beyond any individual's capacity
• •Intonation adjusted to the chord rather than to a keyboard, since a choir singing unaccompanied naturally tunes intervals purely, which sounds better and causes the pitch to drift

Unaccompanied choirs tend to go flat, and the reason is partly acoustic and partly physical. Pure tuning, in which intervals are adjusted to simple frequency ratios rather than to the compromise of equal temperament, produces a beautiful sound and means that a sequence of chords can accumulate a downward shift, since the arithmetic of moving through certain progressions in just intonation does not return to the starting pitch. Fatigue and poor breath support contribute more in practice, since a tiring singer drops the larynx and loses support, which flattens pitch. Warm rooms, dehydration and long rehearsals make it worse. Conductors manage it by giving the pitch periodically, by attending to breath support and vowel brightness, and by accepting a small amount of drift as the price of pure tuning, which many choirs and audiences prefer to the alternative.

Choral singing in the European tradition grew out of liturgy, and the institutional structures still visible date from that. Plainchant sung in unison by monastic communities is the oldest layer, polyphony developed from the twelfth century by adding independent lines, and the Renaissance produced the unaccompanied sacred repertoire that remains the technical foundation of choral training. Cathedral and collegiate foundations maintained professional choirs with choir schools, an arrangement that survives in Britain and produced the treble sound associated with it, and which excluded girls entirely until the 1990s, when the first cathedral girls' choirs were founded against considerable resistance. The Lutheran tradition gave congregational singing a central place and produced Bach's cantatas. The nineteenth century created the amateur choral society, which is where the enormous oratorio choruses come from and which remains the largest participatory musical activity in many countries. Outside Europe, choral traditions developed independently and differently, including the South African isicathamiya and the gospel traditions of the American South, which arrange and blend voices on completely different principles.

Choral singing is one of the most widespread amateur activities anywhere, and the research on its effects is unusually consistent. Group singing has been found to synchronise heart rates among participants, to raise measures of social bonding, and to improve reported wellbeing, with the effects appearing regardless of whether participants consider themselves good singers, which points at the collective activity rather than at musical achievement. Programmes for people with dementia, with Parkinson's disease and with respiratory conditions have measurable results, the last because sustained controlled exhalation is exactly what breathing rehabilitation asks for. The wider explanation offered is that synchronised group activity is an old bonding mechanism and singing is a particularly demanding form of it, requiring people to coordinate breath, pitch and timing continuously while listening to each other, which is close to a definition of cooperation.

A choir does not sound like a louder soloist because slight differences in pitch and timing between voices produce a chorus effect, and choral technique is about controlling it. Blend depends on unified vowels, matched consonant timing, restrained vibrato, listening outward and staggered breathing, and unaccompanied choirs drift flat because pure tuning does not always return to its starting pitch and because fatigue flattens support. The European tradition grew from liturgy through monastic institutions and the nineteenth-century amateur choral society, and group singing measurably improves wellbeing regardless of ability.