To promote active participation, the people should be encouraged to take part by means of acclamations, responses, psalmody, antiphons, and songs, as well as by actions, gestures, and bodily attitudes. And at the proper times all should observe a reverent silence.
The sixth mention of active participation, and contrary to what liturgical revisionists will tell you, the council actually gives examples of what it means. Active participation includes singing, as well as actions and attitudes. Silence is naturally part of this understanding, as earlier in SC we read about “full” participation.