Show HN: Eigendrum - Draw any shape and hear what it sounds like as a drum • Hacker News Board

Show HN: Eigendrum - Draw any shape and hear what it sounds like as a drum

#1

Post by BaselAshraf81 » Mon, Aug 10, 2026, 4:53 PM UTC

Hi HN, I built Eigendrum, a web tool that solves the 2D wave equation for arbitrary shapes so you can hear what they sound like as drums.

How it works: * Solves -∇²u = λu using finite element analysis (Kφ = λMφ) on a triangle mesh. * Validated to Repo and tests: https://github.com/BaselAshraf81/eigendrum

Happy to answer any questions about the FEM solver or Web Audio setup!

https://eigendrum.com/#p=circle

Show HN: Eigendrum - Draw any shape and hear what it sounds like as a drum
baselashraf81.github.io

Re: Show HN: Eigendrum - Draw any shape and hear what it sounds like as a drum

#2

Post by [deleted] » Mon, Aug 10, 2026, 5:28 PM UTC

[deleted]

Re: Show HN: Eigendrum - Draw any shape and hear what it sounds like as a drum

#3

Post by andai » Sat, Aug 15, 2026, 12:45 AM UTC

Very cool. Number keys and QWERTYU (or clicking the rows on the right) trigger the "modes" in isolation, which are surprisingly microtonal.

Also you can draw your own drums! What! That's so cool

Re: Show HN: Eigendrum - Draw any shape and hear what it sounds like as a drum

#4

Post by Jeff_Brown » Sat, Aug 15, 2026, 12:58 AM UTC

I love it. I wish I could select materials.

Re: Show HN: Eigendrum - Draw any shape and hear what it sounds like as a drum

#5

Post by BaselAshraf81 » Sat, Aug 15, 2026, 1:34 AM UTC

Thanks for reposting this! I'm the developer (BaselAshraf81) - happy to answer questions or hear suggestions here.

If you find it interesting, a star on the GitHub repo helps a lot.

And don't forget to follow me on github, I build cool stuff!

Re: Show HN: Eigendrum - Draw any shape and hear what it sounds like as a drum

#6

Post by tanderson92 » Sat, Aug 15, 2026, 1:38 AM UTC

Jeff_Brown wrote: post #4

I love it. I wish I could select materials.

Selecting different materials would not change much. Call the frequencies \lambda_1, \lambda_2, \lambda_3...

You can prove that changing the material has no effect on the relative frequencies: \lambda_2 / \lambda_1, \lambda_3 / \lambda_1, etc. are completely independent of the material.

The shape is the determining factor; changing the materials (and hence the wave speed) just dilates the whole spectrum.

Re: Show HN: Eigendrum - Draw any shape and hear what it sounds like as a drum

#7

Post by BaselAshraf81 » Sat, Aug 15, 2026, 1:40 AM UTC

Jeff_Brown wrote: post #4

I love it. I wish I could select materials.

There's actually a "ring-out" slider and a "mallet" width slider under the drum already.

Ring out controls how fast the higher modes decay (basically stiff vs soft material), The mallet width controls how many modes a strike can even reach, since a real mallet can't drive the high frequency ones very hard.

No labeled presets like "wood" or "metal" though, just raw sliders. Would be a fun addition if someone wants to map a few physically sensible combos to buttons. PRs Welcome!