"But the Lord is in his holy temple: let all the earth keep silence before him" says the prophet Habakkuk. Today we live in a world where this kind of thinking is anathema. When you are in the presence of one you respect greatly, you defer to them. You give them the honor that is due to them, and you would want nothing you do to detract from their rightful honor. One could say that our current liturgical consciences are infected with this sickness. We must always have some sort of noise going on at Mass, since we try to make ourselves the center of attention. Before he became Pope Benedict XVI, Cardinal Ratzinger said the following about the way modern man approaches the Mass and the Eucharist:
How often do we celebrate only ourselves, without even realizing that he is there! How often is his Word twisted and misused! What little faith is present behind so many theories, so many empty words!
There are those who will have things running simply as "background noise" for to sit in silence is abhorrent. It is in silence that we truly "hear" our souls. With no distraction, we will end up reflecting on ourselves and on those things around us. We will recognize the pointlessness of so much minutiae. Hopefully, we learn to listen to God in place of these disturbances. Elijah did not perceive the presence of God until he perceived the "stillness" in the air.
Finally, silence is an affirmation of our human weakness in the sight of God's majesty. Nothing we understand can fully comprehend the mysteries of God. As Alice Von Hildebrand said of such instances "silent adoration is the only response."
That silence at Mass is most profound during the canon of the Mass, where almost all of it is prayed in silence by the priest. Such silence is meant to be a signal for us that something very important is transpiring. Up until this point, the liturgy could be called a work of man. At the consecration of the Eucharist, it becomes a work of the Holy Spirit. Only through the Holy Spirit does the change in substance take place. I could walk up to the altar and say those words all I want, but it would still remain just bread. Only in the priest (who receives the Holy Spirit in a very particular manner to offer said sacrifice) can the consecration occur. Even then, it is not the priest who is saying these words, but Jesus Christ acting through the priest. (The Latin refers to it as in persona Christi, in the person of Christ.)
What could we possibly add to this with our noise?