Your hands are the harmony
No BS autotune guessing the key (small stray to Antares)
hi, i’m adam.
im an aspiring musician, producer, whatever (artistically)
i also like jacob collier and so this one time i was was watching youtube shorts and i saw this video about the harmonizer he plays live and it like really inspired me i was like this algorithmically seems pretty straightforward
i looked into the research this phd student from MIT Ben Bloomberg did on this to build jacob’s harmonizer
it uses live resampling polyphonic synthesis
custom electronics and a dismantled TC helicon processor into a single box controlled via a midi keyboard or whatever. i made it my mission to make this accessible to all harmony enjoyers (and bad singers)
so in july of 2026 i started building my own
here it is:
The Specs (literally)
01 pitch.track
// f0 estimation, per frame
const f0 = yin(frame, {
window: "hann",
interp: "parabolic",
guard: "octave"
});
// cumulative mean normalized
// difference functionShow summary
pitch detection is built to be low latency so it hears what note you are sining almost instantly
02 voices.shift
for (const note of midi.held) {
const r = 2 ** ((note - f0) / 12);
out += psola(grains, r);
}
// pitch synchronous
// overlap add, epoch
// aligned grainsShow summary
every key you press instantly resamples an instant of your voice and tunes it to that note
03 formant.lock
const env = lpc(frame, order);
voice = warp(voice, env, 1 / r);
// spectral envelope
// preserved per voice
// no chipmunks. ever.Show summary
the formant shaping algorithm preserves your timbre and spectral envelope so u wont sound like a chipmunk (unless you like that which in which there is a convenient dial in the plugin)
04 midi.route
midi.on("noteOn", n =>
voices.allocate(n));
midi.on("noteOff", n =>
voices.release(n));
// your keyboard IS
// the harmonyShow summary
the whole engine is fed midi, so external control and polyphonic aftertouch is integrated into the software through automation
export default harmonizer(); // put it together: this cool app
