About 50 years ago, Lake Erie froze and became covered with a glassy sheet of ice about 50 millimetres thick. As an onshore wind rose, I heard the lake sing with a pure, mid-range, organ-like tone, which rapidly intensified to an almost intolerable level with no visible motion in the lake. After a few minutes the ice fractured and the pure tone was replaced by cracking, echoing at about the same pitch and, abruptly, by the atonal roar of shattering ice. Has anybody else witnessed such an event? How was the tone created?Charles Sawyer, Camptonville, California, US