Vocal harmony

Vocal harmony is a way of singing where one or more notes that sound pleasing together are sung at the same time as the main melody, usually with the melody as the focus. This technique appears in many types of Western music, from classical choral works and opera to folk songs, musical theater, and rock ballads. The simplest form has a single backup voice singing above or below the lead, often at intervals of a third or sixth that match the song's chords. More complex arrangements may have two or three backup singers each adding different notes, mostly using thirds, sixths, and fifths for a smooth sound, though short dissonant notes can appear as passing tones.

In art music

In art music, vocal harmony became important during the Renaissance, when Mass melodies were harmonized with sweet thirds and sixths. Later, in Lutheran churches, congregations sang hymns arranged in four or five parts.

During the Romantic era of the 1800s, vocal harmonies grew more complex and included more dissonance. Operas and choral works from that period used tense-sounding augmented and diminished intervals to heighten drama. In the 1900s and 2000s, composers pushed choirs further, asking for microtonal notes or percussive sounds.

In popular music

In popular music, backup singers must stay in tune with the lead vocalist and the band’s instruments, and their rhythm must match the lead and rhythm section. Some bands use simple, slow-moving harmony notes during choruses, while others treat backup singers as equal partners, demanding vocal agility and sensitivity similar to the lead. Usually, harmony vocals are sung while the band plays, but some rock and pop songs use a cappella sections without instruments. This effect became common in the final choruses of 1980s and 1990s hard rock and heavy metal ballads, as well as in horror punk, which draws from both heavy metal and doo-wop.

Other roles

Backup singers often have other stage roles. In rock and metal bands, they may play instruments like keyboards, rhythm guitar, or drums. In Latin or Afro-Cuban groups, they might play percussion or shakers while singing. In pop, hip-hop, and musical theater, backup singers may perform choreographed dance routines while using headset microphones.

Barbershop quartets

One complex style is the barbershop quartet, which harmonizes a melody in four parts. The lead sings the melody, the tenor harmonizes above, the bass sings the lowest notes, and the baritone completes the chord, usually below the lead. The melody is not typically sung by the tenor or bass. Barbershop quartets use dissonant dominant seventh chords more often than pop or rock bands.

Doo-wop is a vocal-based rhythm and blues style that began in African-American communities in the 1940s and became popular in the U.S. from the 1950s to the early 1960s. It features smooth, consonant harmonies, with singers imitating instruments using nonsense syllables.

For instance, in The Ravens’ “Count Every Star” (1950), singers mimic the “doomph” sound of a double bass. Notable hits include “In the Still of the Night (I Remember)” by The Five Satins and “Get a Job” by The Silhouettes (1958). Doo-wop remained popular until just before the British Invasion of 1964.