Interestingly, though, the ceremonies of the usus antiquior provide little in the way of pauses for silence. The "silence" that people love so much is mostly when the priest is praying secreto, that is to say, he vocalises the words in such a way that he can hear them but others don't. Thus the "silence" is a more or less determined length of time which comes to an end when the priest reaches the next part that is to be said out loud or sung.
In the older form of Mass, there are three moments where the priest pauses in silence. At the memento of the living in the Canon, he remains for a short time in silence, remembering those for whom he wishes to pray (stat paulisper in quiete). In this case, the rubric explicitly says that he does not need to express the names but may remember them in his mind. The instruction for the memento of the dead says that he remembers them in the same way (though now that the sacred host has been consecrated, he is instructed to look at the host.) In fact, the priest may have many names or classes of people he wishes to remember and may simply recall in general those for whom he has made an intention to pray during his preparation for Mass. When people ask for my prayers, I usually promise to remember them at my Mass in this way.
The third pause for silence in the usus antiquior is after the priest has consumed the sacred host (not after he has received Holy Communion from the chalice.) He is instructed to be quiet for a short time in meditation on the most holy Sacrament (aliquantulum quiescit in meditatione sanctissimi Sacramenti).
The Missal of Pope Paul VI provided for more pauses for silence; though you might not realise this since the overall impression of the Mass is that there is virtually no silence since the Eucharistic Prayer is said out loud, something that Gueranger deplored: Cardinal Ratzinger suggested that an option should be provided for saying it quietly. Very often the Offertory is also said out loud as well, so that the only time when there is a prayer of any length said secreto is before the priest's Communion. In fact, many priests, I think, feel slightly embarrassed at this and rush the prayer or say it out loud. The pauses for silence are detailed in the General Instruction of the Roman Missal (GIRM - I will refer to the edition promulgated with the 3rd edition of the Missale Romanum in 2002)
In the section on the Liturgy of the Word, there is a heading "Silence" and the monition that it is appropriate to have "brief periods of silence" (brevia momenta silentii) before the Liturgy of the Word begins, after the first and second readings and after the homily. (GIRM 56) The priest's own pause for silence after consuming the sacred Host is not in the rubrics though I think we might allow it to the priest without denouncing him as being just as bad as priests who say clown Masses and make up their own Eucharistic Prayer.
In the section headed "Communion", the Instruction says that when the distribution of Communion is finished, if appropriate (pro opportunitate), "the priest and faithful spend some time praying quietly." (sacerdos et fideles per aliquod temporis spatium secreto orant). (GIRM 88)
This silence for "some time" is an innovation: in Italy, it is known as the pausa. I am not sure that it always works very well. One danger is that it becomes an impromptu directed meditation. Paulinus has an amusing account of this in his post Witter, witter, witter... which prompted me to write this post.
The other problem is that if the pausa is genuinely quiet, nobody knows how long it will last. It is very much at the discretion of the priest, and people are left wondering "When is he going to start again?" rather than engaging in considerations, affections and resolutions, or resting in infused contemplation, depending on their spiritual state.
My own practice is to consider (as I suspect most parish clergy do) that the four pauses at the Liturgy of the Word are not really suited to the normal parish Mass. In particular, at the conclusion of my sermon, rather than sit and ponder my words of wisdom (howsoever brilliant they may be) I feel it better to direct people to the "action of God" that is to take place, "Conversi ad Dominum!" as St Augustine would say, (it was the beginning of a prayer) reminding them that the Sacred Liturgy is focussed on God.
After Communion, though, it seems to be a more general practice to have some time for silent prayer. My own practice is to purify the vessels with wine and water, using the option provided in GIRM 279. This paragraph does not specify how this is to be done but we are fortunate to have older books which give the instructions in greater detail; there is also an extra prayer which it is surely legitimate to use quietly if there is time (there always is). Again, I feel reasonably sure that this is not the first step on the road to dressing up as Barney the Bear.
The purification all being done quietly (the prayers said secreto), there is a reasonable time of silence for the people. In order to keep to the letter and spirit of the pausa instruction, I then remain at the altar and say quietly the Placeat tibi prayer so that the pausa is observed but of a determinate length. I remain at the altar because I have observed that if the priest goes to sit down, everyone who was formerly kneeling follows suit as though it were a form of instruction to them. If the priest remains standing at the altar, it leaves the People of God greater freedom in the Spirit, surely?
Let me conclude with a passage from the writings of Cardinal Ratzinger that was quoted by Mgr Marini in his address to the Confraternity of Catholic Clergy in Rome this year:
Fish live in the sea and are silent. Terrestrial animals cry out, but the birds, whose vital space is the heavens, sing. Silence is proper to the sea, crying out to the earth, and singing to the heavens. Man, however, participates in all three: he bares within him the depth of the sea, the weight of the earth, and the height of the heavens; this is why all three modes of being belong to him: silence, crying out, and song. Today...we see that, devoid of transcendence, all that is left to man is to cry out, because he wishes to be only earth and seeks to turn into earth even the heavens and the depth of the sea. The true liturgy, the liturgy of the communion of saints, restores to him the fullness of his being. It teaches him anew how to be silent and how to sing, opening to him the profundity of the sea and teaching him how to fly, the nature of an angel; elevating his heart, it makes that song resonate in him once again which had in a way fallen asleep. In fact, we can even say that the true liturgy is recognisable especially when it frees us from the common way of living, and restores to us depth and height, silence and song. The true liturgy is recognisable by the fact that it is cosmic, not custom made for a group. It sings with the angels. It remains silent with the profound depth of the universe in waiting. And in this way it redeems the world.”