When we sing, air expelled from our lungs causes the vocal cords (two strips of cartilage stretched across the larynx at the back of the throat) to vibrate like reeds, and so produce a note. To sing a higher note, we tighten the vocal cords; to sing a lower note, we slacken them. The various cavities of our throat, mouth, nose and head, serve as resonators to amplify and enrich the sounds.
The following names are used to describe the range, and also the timbre, of different types of voices. For each voice, the average range is shown – trained soloists would be expected to exceed these limits. (Music for tenor voice is sometimes written in the treble clef, one octave higher than the actual sounds.) Males singers can be either bass, baritone, tenor or counter-tenor.
A countertenor is an exceptionally high male voice with a strong, pure tone. It was popular in England during the 17th and 18th centuries, and has been revived during the 20th century.
Female singer voices fall into three categories of alto/contralto, mezz-soprano or soprano.
A boy’s voice before it ‘breaks’ (meaning that the vocal cords thicken, causing the pitch to become lower) is described as either a treble (high range) or alto (low). Girls’ voices are similar in range, but have a rather gentler tone.
Various groups of voices may be combined to form a chorus or choir. The most usual kind consists of ‘mixed’ voices – groups of sopranos, altos, tenors, and basses. A female choir includes two groups of sopranos and one or two groups of altos. A male voice choir may consists of men’s voices only, or of boys’ and men’s voices mixed together – trebles, altos, tenors, and basses.
Solo voices may combine to sing a duet (for 2 voices), trio (3), quartet (4), quintet (5), sextet (6).