Readers of Stuff’s post on singing before/during/after communion may find these interesting.
[…]In any case, the first use of actuosa participatio, i.e., active participation, referred explicitly and exclusively to the restoration of the congregational singing of Gregorian Chant. In 1928, Pope Pius XI reiterated the point in his Apostolic Letter, Divini Cultus. Nineteen years after that, in the Magna Carta of liturgical reform, Mediator Dei, issued by Pius XII, the same term was used with the same meaning. So until the Second Vatican Council, the term “active participation” referred exclusively to the singing of Gregorian Chant by the people.
42. In the ars celebrandi, liturgical song has a pre-eminent place. (126) Saint Augustine rightly says in a famous sermon that “the new man sings a new song. Singing is an expression of joy and, if we consider the matter, an expression of love” (127). The People of God assembled for the liturgy sings the praises of God. In the course of her two-thousand-year history, the Church has created, and still creates, music and songs which represent a rich patrimony of faith and love. This heritage must not be lost. Certainly as far as the liturgy is concerned, we cannot say that one song is as good as another. Generic improvisation or the introduction of musical genres which fail to respect the meaning of the liturgy should be avoided. As an element of the liturgy, song should be well integrated into the overall celebration (128). Consequently everything – texts, music, execution – ought to correspond to the meaning of the mystery being celebrated, the structure of the rite and the liturgical seasons (129). Finally, while respecting various styles and different and highly praiseworthy traditions, I desire, in accordance with the request advanced by the Synod Fathers, that Gregorian chant be suitably esteemed and employed (130) as the chant proper to the Roman liturgy (131).
62. None of the above observations should cast doubt upon the importance of such large-scale liturgies. I am thinking here particularly of celebrations at international gatherings, which nowadays are held with greater frequency. The most should be made of these occasions. In order to express more clearly the unity and universality of the Church, I wish to endorse the proposal made by the Synod of Bishops, in harmony with the directives of the Second Vatican Council, (182) that, with the exception of the readings, the homily and the prayer of the faithful, it is fitting that such liturgies be celebrated in Latin. Similarly, the better-known prayers (183) of the Church’s tradition should be recited in Latin and, if possible, selections of Gregorian chant should be sung. Speaking more generally, I ask that future priests, from their time in the seminary, receive the preparation needed to understand and to celebrate Mass in Latin, and also to use Latin texts and execute Gregorian chant; nor should we forget that the faithful can be taught to recite the more common prayers in Latin, and also to sing parts of the liturgy to Gregorian chant. (184)