Rhythms You Can See, Colors You Can Hear

Play three against four fast enough and your ear stops counting. It starts hearing a chord. polyrhythmic.design is a suite of apps that let you play with this concept.

In 1962, Swiss designer Karl Gerstner built a grid for Capital, a German business magazine. Fifty-eight units. One page could split into three columns, or four, or five, and look great. Turns out he was designing with a major chord.

Three columns and four columns meet at 12. Add five, and they meet at 60.

In 2017, bassist Adam Neely took the stage at Ableton Loop in Berlin and walked a room from rhythm to pitch to color. Newton’s prism. Scriabin’s colored chords. One set of ratios underneath all of it.

Play 4 against 5 against 6, then speed it up. It becomes a major triad.

Double a note and you get the same note, one octave higher. Double A440 forty times and you leave sound behind. You land near 484 trillion cycles per second: orange-red light.

The whole rainbow fits inside a single octave, almost. Two notes sit right at the edge. F, around 390 nm, is the last violet most eyes can catch, and only faintly. F♯, around 368 nm, is ultraviolet: invisible to us, though a bee could see it.

Pink has no wavelength either. Your brain invents it where red meets violet. So F♯ borrows pink, a made-up color for a note you can’t see. Which may explain why singing in F♯ feels like reaching for a note that isn’t quite there. Tim Minchin wrote a whole song about it: “F Sharp,” BBC Proms 2011.

No monitor can show pure spectral light. It mixes red, green, and blue and gets close. To get from a wavelength to that mix, I use an algorithm by Dan Bruton: a short program he shared freely online that turns any visible wavelength into an approximate RGB color. It’s been translated into many languages since, and it turns up in physics teaching demos, spectrum plots and typesetting tools.

HSL then hands that mix back to a musician.

Color wheels come in many kinds. Painters’ wheels follow how pigments mix. Screen wheels follow red, green and blue. The first color circle came from Isaac Newton, in Opticks (1704). He built it from the spectrum, and split it into seven colors to match the seven notes of a musical scale.

Others have raised notes into light by octaves before. This wheel follows the light itself: every note sits where its frequency falls and takes its real color from its wavelength. Saturation becomes noise, and lightness becomes volume. The shapes you draw on it are chords.

Here’s a C major chord, C, E and G, on two wheels: green, violet and a red that leans pink. Slow it down and you hear a groove. Speed it up and you hear harmony.

The two wheels hold the same colors. They just disagree about distance. The light wheel spaces notes by how their colors look; the pitch wheel spaces them by how they sound.

Polymeter and polyrhythm grow from the same root and split at the beat.

In polymeter, every lane keeps the same pulse and loops at its own length. A three-step loop and a four-step loop drift apart, then meet again every twelve steps.

In polyrhythm, every lane shares one bar and stretches to fill it. Three hits and four hits land in the same span of time.

I looked for a drum sequencer that flips between the two with one switch. I couldn’t find one. So I built polytoggle.

Flip it and hear one pattern two ways. A teacher can show the difference in a single click. A producer can wander into rhythms with no names yet.

Rhythm, pitch, light, and a magazine grid display the beauty of math in music, proof of intelligent design, to me at least.

Play three against four in polytoggle and watch it turn into color.