- Author
- Basel Ashraf
- Published
- Undated
- Kind
- Interactive web tool with a built-in explanation
- Original
- eigendrum.com/
- Subject
- Music tools and instruments
What it is
Eigendrum is a free web tool by Basel Ashraf. A user draws an outline, or types a polar or parametric formula. The page finds the drumhead's vibration modes for that outline and plays them.
What it says
- Eigendrum turns a drawn, polar or parametric outline into a drumhead and plays its modes.
- The tool solves for modes numerically, using a triangle mesh and finite element matrices.
- The page says the solver is tested against circle and rectangle spectra on every change. It reports agreement to better than a tenth of a percent.
- Strike position matters, because modes with a nodal line under the mallet stay silent.
- Gordon, Webb and Wolpert built two shapes with identical spectra in 1992. Both are offered as Kac drums.
- Shapes are scaled to equal area. Pitch then spreads roughly six semitones across presets.
- Damping rises with frequency squared, so high overtones die first and the drum darkens.
What evidence it gives
The page gives its method and cites Kac, Gordon, Webb and Wolpert, and Driscoll. It reports tests against shapes with known exact spectra. It offers no listening study and no outside measurements.
Interests and limits
This is one developer's own description of a tool that developer made. The page asks for donations and offers ad space for rent. The text was read in full, but the sound and the interface were not tried. The accuracy claims were not independently checked.