A cappella

A cappella is music performed by voices without instrumental accompaniment. Singers may use only melody or combine melody, harmony, rhythm, and vocal percussion.

Vocal harmony: The simultaneous combination of distinct sung notes to create chords and harmonic texture. Multiple vocal parts can provide the chordal foundation that instruments might otherwise supply.
A cappella (music genre): A style of popular vocal music performed without instrumental accompaniment, often by organized groups. The modern genre gives the old performance designation a distinct popular-music identity.
Madrigal: A secular vocal composition, especially one from the Renaissance, often written for several independent parts. Renaissance madrigals demonstrate intricate ensemble music composed for voices without instruments.
Accompaniment: Musical support provided by one or more parts alongside a principal melody or singer. Its presence distinguishes accompanied vocal music from a cappella performance.
Overtone singing: A vocal technique that makes one overtone stand out alongside a lower sustained pitch. It lets one singer produce a drone and a distinct high melodic tone at once.
Gregorian chant: The monophonic liturgical chant of the Roman Catholic Church's Latin rite. Its unaccompanied singing is a longstanding example of vocal music in worship.
Spiritual (music): A genre of religious folk song created by African Americans, especially during slavery in the United States. Spirituals are often performed unaccompanied and shaped traditions of communal vocal music.
Aria: A solo vocal piece, usually with instrumental accompaniment, in an opera or oratorio. A solo aria commonly pairs a singer with instruments rather than relying on voices alone.
Vocal percussion: The imitation of percussion sounds using the mouth, lips, tongue, and voice. It can provide a rhythmic pulse in ensembles that use no instruments.
Renaissance music: European art music composed roughly between the fifteenth and early seventeenth centuries. Renaissance vocal polyphony is a major historical setting for unaccompanied ensemble singing.

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