"Which monks take a vow of silence?" While we couldn't find the answer in our copy of “The Religions Book,” nor by looking under “monasticism” and “vow” in Merriam-Webster’s “Encyclopedia of World Religions,” searching online turned up a variety of resources.
As it turns out, the Christian monks most strongly associated with silence are the Trappists. However, according to www.trappists.org and www.ocso.org (OCSO stands for “Order of the Cisterians of the Strict Observance,” the less common name for the religious order to which Trappists belong), they never take an actual vow of silence. Rather, they take a vow of conversion, which is a promise to live the monastic way of life and also covers a promise to be celibate and to practice voluntary poverty. While there is a pervasive atmosphere of silence at a Trappist monastery, there are several circumstances where the monks will typically speak. According to www.ocso.org, “there are three reasons for speaking: functional communication at work or in community dialogues, spiritual exchange with one’s superiors or with a particular member of the community on different aspects of one’s personal life, and spontaneous conversation on special occasions.”
For more information, Jeremy Mesiano-Crookston wrote an article called “How Silence Works: Emailed Conversations With Four Trappist Monks." Also, Patrick Leigh Feymor’s “A Time to Keep Silence,” which includes a section about his stay at a Trappist monastery, is available through CLEVNET.