The Sacred Liturgy No. 3

Singing is essential in the Liturgy…
Singing is a sign of the joy of the heart, the joy we experience when we gather in the presence of Christ to pray the Mass. From the earliest days of the Church, singing has been part of Christian worship. (Saint Paul instructed the Colossians to sing "songs, hymns and inspired songs.") Singing is of great importance and should be present in the Liturgy whenever possible. Among the various types of liturgical music, Gregorian chant holds "pride of place," because it is the music proper to the Roman Rite. The Church desires that all Catholics know at least some Latin chants. All liturgical music needs to be carefully planned so that it is in the spirit of sacred worship and encourages participation by the faithful.
Active participation in liturgical singing – chants, vernacular hymns, and responsories – is an expression of our faith and devotion. Recall the ancient proverb: "he who sings well prays twice!"
GIRM 39-41