In his treatise De Anima 9,4 CCL 2, 792, Tertullian writes: Prout scripturae leguntur, aut psalmi canuntur, aut allocutiones proferuntur aut petitiones delegantur. In the old liturgy, then, at least at Rome, singing was limited to the psalms. It is unclear, however, whether the whole psalm was sung. In Augustine’s time and in that of Leo the Great, the lector read the psalm after the epistle and the people would sing a refrain taken from the psalm itself. This explains Augustine’s words: Legenti respondentes cantavimus In ps. 40 enarr. Sermo ad plebem I: CCL 38, 447. The psalm after the first reading seems to have been considered a reading. But gradually the need was felt to respond to the reading, and so the psalm became one of the many forms of responsorial chant. Other forms consisted of a simple acclamation, a poetic composition or a biblical canticle, esp. in the liturgy of the Word during the Easter Vigil. The use of responsorial psalms was common in the time of Augustine and Athanasius Lodi, Enchiridion Clavis, 70, 101-102. The antiphonal chanting of psalms was introduced in the 4th c. at Rome and Milan from the Eastern liturgies. The psalm was divided between two choirs and was introduced and concluded by an antiphon drawn from the psalm itself. Later, the antiphon was also recited in the course of the psalmody. Benedict’s Rule ch. 14 speaks of antiphons ad ipsum diem pertinentes, which shows the existence of a collection of antiphons for the various liturgical feasts. The Roman liturgy has its collections of antiphons for Mass antiphona ad introitum, antiphona ad offertorium and antiphona ad communionem, which indicates that psalms were sung at those moments of the Mass Martimort, The Church at Prayer, 80-81, 113, 188-189.
Source: Tours Maps