Sacred music is an integral part of the liturgy.
Two forms of sacred music are recognised as being perfectly and particularly related to the Roman liturgy: Gregorian Chant and Sacred Polyphony, though Gregorian Chant is to be given pride of place.
To fulfil this principle, there are two divisions of choirs:
The Schola Cantorum Sanctae Crucis, which is the principal choir. The Schola is to ensure that Gregorian Chant retains its pride of place in Solemn Masses on Sundays and feast days.
The Mixed Choir, the Choir of St Radegund; the Ladies Choir, the Choir of Our Lady of Ransom; and the Youth Choir. [A sample of Maternal Heart of Mary St Radegund choir singing IV Kyrie Eleison, in mp3 format.]
The place of music in the liturgy was affirmed by Pope Pius X in his Inter Sollicitudines issued Motu proprio:
In light of this it is easy to understand that the fullness of the liturgy or the normative liturgy of the Church resides in the sung or solemn Mass. This was stated explicitly in De Musica Sacra, issued by the Sacred Congregation of Rites on September 3, 1958: