“Rav Avigdor Miller – His Life And His Revolution” by Rabbi Yaakov Y. Hamburger (p. 190):
Rabbi Miller encouraged his talmidim to learn mussar loudly and enthusiastically, as was the accepted practice in the European yeshivos. Once, when it was too quiet during mussar seder, he joked, “We’re now observing fifteen minutes of silence in honor of the late Reb Yisrael Salanter.”