There are three methods of singing psalms or other chants, responsorial, antiphonal, and solo. In responsorial singing, the soloist (or choir) sings a series of verses, each one followed by a response from the choir (or congregation). In antiphonal singing, the verses are sung alternately by soloist and choir, or by choir and congregation.Weber, Jerome F. "Early Western Chant", Western Catholic Liturgics It is probable that even in the early period the two methods caused the differentiation in the style of musical composition which is observed throughout the later history of plain chant, the choral compositions being of a simple kind, the solo compositions more elaborate, using a more extended compass of melodies and longer groups of notes on single syllables. The last type of plainsong performance is the solo performed by the choir or the individual performer. A marked feature in plainchant is the use of the same melody for various texts. This is quite typical for the ordinary psalmody in which the same formula, the "psalm tone", is used for all the verses of a psalm, just as in a hymn or a folk song the same melody is used for the various stanzas.
