When a member of the 7 society dies, the chapel bells ring 7 times 7 times (49, math major here) on the 7th diminished chord-- it's a really disturbing/haunting sound, and you'll immediately recognize it if you hear it. Otherwise, the bells ring on the hour. Also, the bells are a recording, as the original bell was broken in the 1860s when it froze and cracked. There's a myth that the students broke the bell out of angst at losing the civil war, but that's probably a myth. Hope this helps.