Eigendrum: Draw any shape, hear it as a drum
Original: Show HN: Eigendrum - Draw any shape and hear what it sounds like as a drum
Why This Matters
Demonstrates accessible, browser-based physical simulation of acoustic phenomena using rigorous numerical methods.
Eigendrum is a free, open-source web tool by developer Basel Ashraf that lets users draw any 2D shape and instantly hear it as a physically simulated drum, using finite element analysis to compute real vibrational modes and frequencies.
Eigendrum, available at eigendrum.com, is a browser-based interactive tool that simulates a drumhead of any user-drawn shape. Users can draw freehand outlines, define shapes via polar or parametric equations, or select presets. The tool meshes the shape with triangles, constructs finite element stiffness and mass matrices, and solves the eigenvalue problem −∇²u = λu to find vibrational modes. Each mode is a standing wave; frequencies are proportional to √λ. Up to 16 modes are computed and played simultaneously or individually. Striking position matters: modes with a nodal line under the mallet produce no sound, mirroring real drum acoustics. The solver is validated against analytically known spectra — circle (Bessel function zeros) and rectangle (π²(m²/a² + n²/b²)) — with accuracy better than 0.1%. The project is MIT-licensed, requires no account, and is funded by voluntary donations via Ko-fi and PayPal. Source code is public on GitHub. The tool went viral within a day of its Hacker News post, pushing hosting near its monthly bandwidth limit.