In music, melisma is the technique of changing the note (pitch) of a syllable of text while it is being sung. Music sung in this style is referred to as melismatic, as opposed to syllabic, where each syllable of text is matched to a single note. Music of the ancient cultures used melismatic techniques to achieve a hypnotic trance in the listener, useful for early mystical initiation rites (Eleusinian Mysteries) and religious worship. This quality is still found in much Hindu and Muslim religious music today. In western music, the term most commonly refers to Gregorian Chant, but may be used to describe music of any genre, including baroque singing and later gospel.
Melisma first appeared in written form in some genres of Gregorian Chant, with the earliest written appearance around 900 AD. where it was used in certain sections of the Mass. The gradual and the alleluia, in particular, were characteristically melismatic, for example, while the tract is not, and repetitive melodic patterns were deliberately avoided in the style. The Byzantine rite also used melismatic elements in their music, which developed roughly concurrently to the Gregorian chant.
The hymn tune "Gloria" by Edward Shippen Barnes, to which the hymn Angels We Have Heard On High is usually sung, contains one of the most melismatic sequences in popular Christian hymn music, on the "o" of the word "Gloria".
Melisma is today commonly used in Middle Eastern popular music. Melisma is also commonly featured in Western popular music, which has been heavily influenced by African American musical and vocal techniques, by artists such as Whitney Houston, Stevie Wonder, Luther Vandross, Mariah Carey, Celine Dion, Beyoncé Knowles, Lauryn Hill, Aretha Franklin & Christina Aguilera. Melisma is also used in rock music, with notable proponents including Thom Yorke from Radiohead, Robert Plant from Led Zeppelin, Cedric Bixler-Zavala from Mars Volta, and Trevor Garrod from Tea Leaf Green.