  Chladni patterns of vibrating membranes or thin plates faszinated the people
already in the eighteenth century. As a simple way to visualize acoustic
phenomena it is a valuable experiment for beginners' courses. In this paper I
present NumChladni, an interactive tool for studying arbitrary two-dimensional
vibrating membranes based on the Finite Element method. I also describe the
straightforward approach of the underlying mathematical details and give some
examples. NumChladni is directly applicable in the undergraduate classroom as,
for example, complementary application to experimental setups.
