Silence, both external (a silent place) and internal (the quieting of the heart and mind), is a prerequisite to genuine prayer. It is not simply a question of removing exterior noise but a disciplined willingness to shut off the distractions of the environment, even “good” distractions, in order to listen to the promptings of God in the heart. Silence, in the tradition of prayer, means nothing more than alertness or readiness to receive God; it is another form of saying “yes” to the promptings of God’s self-gift.

Lawrence S. Cunningham
The Catholic Faith: An Introduction (New York: Paulist Press, 1987), pp. 133-4.