Eigendrum

What it does

Eigendrum is a web tool that lets users draw arbitrary 2D shapes and hear what they would sound like as drums. The application solves the 2D wave equation using finite element analysis on triangle meshes to calculate the actual vibration modes for any shape. It factors in where the drum is struck, damping behavior, and mallet width to produce acoustic output that corresponds to the geometry drawn.

The solver has been validated to under 0.1% error against closed-form solutions for circles and rectangles. Users can draw custom shapes, select from preset forms (including parametric equations), or choose predefined examples like Kac drums I and II—shapes that produce identical sound spectra despite different geometries.

Who it is for

The tool appeals to anyone curious about the relationship between shape and sound. Musicians and sound designers could explore how geometry affects timbre. Physics students and educators can use it to visualize standing waves and resonance modes interactively. The no-framework, browser-based design makes it accessible without installation or special knowledge.

Pricing

The site does not show prices. The developer accepts voluntary support through Ko-fi, PayPal, Airtm, and Liberapay.

How it stands out

Most audio synthesis tools generate sound from presets, samples, or mathematical formulas applied uniformly. Eigendrum derives every frequency directly from the shape's real physics. The finite element solver means the overtone pattern emerges from the geometry alone, not from a synthesis algorithm. The interface prioritizes exploration—users immediately hear the consequences of drawing different outlines, and can strike the drum at different points to hear how location changes the perceived timbre due to nodal lines.

What a founder should check

Anyone building a competing tool should verify whether the physics accuracy matters enough to users to justify the computational overhead. Web-based audio synthesis with client-side computation has limits; test whether performance scales acceptably as mesh complexity increases. Second, examine the actual demand: is this a novelty that delights once, or do musicians and educators return repeatedly? Third, explore whether specialized features could build loyalty—exporting audio, integrating with DAWs, or generating 3D models for physical fabrication might differentiate a commercial version from this open-source experiment.