Eigendrum

EIGENDRUM is an interactive study of the vibrating plane. Every shape permits a particular set of standing waves — its eigenmodes — and no others. Draw your own outline, start from an equation, or pick a classic form: a circle, a square, an equilateral triangle, even the famous drums of Kac's question “Can one hear the shape of a drum?”

The exhibit computes the modes of your shape, shows where each overtone falls relative to a perfect harmonic series, and lets you tap the drum anywhere to hear it ring. Modes with a nodal line under the mallet stay silent — which is why the same drum sounds different depending on where you strike it.