Music at Sunday Mass falls into three categories,1)the 'Ordinary', 2)the 'Proper', and 3) hymns.
1) The 'Ordinary' of the Mass is the music that is the same each week, namely, the 'Kyrie' (Lord have mercy upon us), the 'Gloria in excelsis' (Glory be to God on High), the 'Credo' (I believe in one God), the 'Sanctus' (Holy, holy, holy) and the 'Agnus Dei' (Lamb of God). With the exception of the 'Gloria', which is omitted during the penitential seasons of Advent and Lent, these are sung throughout the year. As a general rule we aim only to use settings in which the congregation can join with the choir. We use composed settings by John Merbecke, Martin Shaw, L.J.White and Leo Sowerby.
Saint Chad's is noted for its singing of plainsong, (sometimes known as Gregorian chant) which is the ancient and traditional music of the Christian church. Plainsong uses a very limited number of notes, and is much easier to learn than many people imagine. Some of the chants (for instance, 'Kyrie orbis factor') date back to the tenth century, whilst others - such as the well known 'Missa de Angelis' contain sections written in the fifteenth century. Their melodies are timeless and beautiful, and very fitting for a church as old as Saint Chad's.
2) The 'Proper' of the Mass contains those sections that vary week by week. The 'Introit' is sung as the priest and servers enter, and the altar is venerated; the 'Gradual' and 'Alleluia' after the Epistle is read, and before the Gospel, the 'Offertory', as the bread and wine are taken to the altar, and the 'Communion', sung after the priest has received the Blessed Sacrament. The text of these 'Propers' come mainly from the Book of Psalms. The 'Introit' and the 'Communion' both have an 'Antiphon' which is a section that is repeated before and after the lines from the Psalm. The text of the Antiphon can be taken from the Psalm itself, or from another relevant section of the Scriptures.
The Propers are usually sung by the cantor (soloist) and choir alone, normally to plainsong. The 'English Gradual' pioneered a simple system of chants which use the same music each, but at Saint Chad's we sometimes sing the original plainsong melody with its Latin text, and sometimes a polyphonic (for instance, four part) motet if it contains the appropriate text. From time to time we might sing a devotional piece of plainsong, such as 'Ave verum' or 'O sacrum convivium', or a plainsong hymn suited to the festival or season.
A more recent development, which changes each week, but is not part of the Proper, is the singing of a Psalm between the first reading, (usually Old Testament, except during Eastertide) and the second reading (the Epistle always taken from the New Testament). Here we have a number of musical formats to choose from. There is plainsong (in English), Anglican chant, (itself a development of plainsong), a responsorial setting, alternating between cantor/choir and congregation, or a metrical Psalm (a well known example being 'O God our help in ages past').
3) In the majority of churches congregational Hymns have replaced the 'Propers'. The singing of composed hymns in English was pioneered by the reformed and free churches. Not until after the changes introduced by the second Vatican Council in the 1960s did they take root in the Roman rite. (Among the changes was the translation of the Mass into English). At Saint Chad's we manage to combine the use of both 'Propers' and hymns. We sing a hymn as the altar party enter, and then move on to the 'Introit' as the altar is censed. A second hymn is sung after the 'Offertory', whilst the collection takes place (in 19th century France it was popular to play a rousing piece of organ music at this point - hence the number of collections of organ music that contain pieces entitled 'Offertoire'). Another hymn is sung after the choir have finished the 'Communion'. The final hymn is sung after the blessing, during which the altar party and the choir process to the statue of Our Lady at the back of the church. Then before the final dismissal there is a devotion to Mary, normally the 'Angelus' (The Angel of the Lord declared unto Mary) which may be said or sung. This consists of responses between priest and people, three Hail Marys and a final collect. Sometimes we sing the traditional Marian antiphon 'Salve Regina' (Hail, holy Queen). During Eastertide we sing the 'Regina Caeli'(Joy to thee, O Queen of Heaven).
Where possible, and in keeping with the ancient tradition of the church, both the Ordinary and the Proper are sung without accompaniment during Advent and Lent. There is no organ music, and only the hymns are accompanied. On Good Friday the entire liturgy is sung without the organ. during the rest of the year organ voluntaries are played before and after Mass.