" Lastly- and this was the most pitiless torture of all- we heard the rain and it was not raining! This was an infernal invention... Oh, I knew well enough how Erik obtained it! He filled with little stones a very long and narrow box, broken up inside with wooden and metal projections. The stones, in falling, struck against these projections and rebounded from one to another; and the result was a series of pattering sounds that exactly imitated a rainstorm. "

― Kate McMullan , The Phantom of the Opera (Bullseye Chillers)