What holds priority when it comes to singing during the liturgy? The “Instruction on Music in the Liturgy (Musicam Sacram)” holds three degrees of importance.
The First Degree: Order of the Mass
Entrance rites: greeting of the priest together with the response of the people
Liturgy of the Word: acclamation at the Gospel
Liturgy of the Eucharist: prayer over the offerings, preface and its accompanying dialogues, Sanctus (Holy, Holy, Holy), final doxology of the canon, Lord’s Prayer, the sign of peace, prayer after Communion, and formulas of dismissal
The Second Degree: Ordinaries of the Mass
Kyrie, Gloria, Agnus Dei (Lamb of God)
Creed
Universal Prayer (Prayer of the Faithful)
The Third Degree: Propers of the Mass
Chant or song during the entrance and Communion processions
Psalm after reading
Alleluia before the Gospel
Song at the offertory
Chanting of the Readings
This tells us that the simple dialogues between the celebrant and assemblies are the most important whether they are chanted or spoken. Out of these two, chanted is favored.
The Principle of Progressive Solemnity is suggested in the “Sing to the Lord” document published by the USCCB. In quoting “Musicam Sacram,” 7, “between the solemn, fuller form of liturgical celebration, in which everything that demands singing is in fact sung, and the simplest form, in which singing is not used, there can be various degrees according to the greater or lesser place allotted to singing”.