The Vocal music reference article from the English Wikipedia on 24-Apr-2004
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Vocal music

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Vocal music is music intended for performance mainly by singers. Other musical instruments may be involved, but the choir is the main focus of the piece. Examples of vocal music include choral music, yodeling, and Barbershop.

Vocal music is probably the oldest form of music, since it does not require any other instruments other than the human voice. All musical cultures have some form of vocal music.

See also: a capella.