In the late 80s I worked in a low cluster of buildings, each of which was topped with a band of vertical ridges spaced about 4" apart (sort of like a corrugated roof, but with vertical corrugations). One day a thunderstorm came through, and we discovered that the pulses of thunder, when they hit the corrugations, reflected as a quickly falling tone. The corrugations were working as an acoustic diffraction grating, with different frequencies reflecting in different directions.

Very neat, this reminds me of the organic shapes of passive demultiplexers in photonics such as https://pubs.acs.org/doi/10.1021/acsphotonics.7b00987

Brainstorming applications of knowing your angle relative to a point source:

- adaptive sports for visually impaired players like beep baseball?

- robot swarm members knowing their relative 2d position with a single microphone? (frequency for angle, amplitude for distance)

- a cheap, durable way for human workers to track the rotation cadence of slowly rotating machinery?

okay who wants to build a musical instrument that works by beaming white noise at a bunch of these things, with some way for the user to rotate them quickly and accurately

How the heck do you arrive at such a crazy shape wow this is amazing.

This is the kind of thing that keeps me coming back to HN more often than I should. So cool.

One more step toward building the pyramids.

Whoa it's like an ear but for light!