Chord Progressions

A functional-harmony transition matrix, not a random draw — so it sounds written.

audio.chord · v1 · renderer audio

0:00 / 0:00

C3 major · I vi I IV V I V I · 8 bars at 84 BPM · Pad (slow, glassy)

Drawn from the transition matrix in docs/09 §8: chords move down a fifth far more often than anywhere else, and the final two bars are a cadence rather than a draw. That is the whole difference between this and a random chord picker.

[data-audio-stage] { display: none; }

Synthesised in the browser

No audio file crosses the wire. The server sends a score — the events, envelopes and synthesis parameters below, plus a 32-byte key — and the samples are made here, from the same byte stream the server would have used. A four-minute piece is about two kilobytes of JSON. That needs JavaScript, so with it switched off there is nothing to play.

The score itself is still public: /api/v1/g/audio.chord returns it, and the synthesis is in resources/js/audio.

C3 major · I vi I IV V I V I · 8 bars at 84 BPM · Pad (slow, glassy)

entropy in

16 bytes

stream used

98 bytes

rejections

duration

203 µs

progression

I → vi → I → IV → V → I → V → I

key

C3 major

cadence

V → I (authentic)

voicing

Close (root position)

duration

25.4 s

Seed receipt

Class B · Public beacon cached

NIST Beacon pulse #1,939,959 — chained to every pulse before it, and signed.

Published openly — anyone can look this value up after the fact.

source: NIST Randomness Beacon
observed: 2026-09-13T18:45:00+00:00
latency: 0ms
mixed with: csprng — always

https://beacon.nist.gov/beacon/2.0/chain/2/pulse/1939959 ↗

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The token is the seed, so this link recomputes the result rather than looking it up. No database, and it works for as long as v1 does.

Controls · from schema()

Key

Mode

Octave

2 4

Bars

4 16

One chord per bar. The last two are the cadence and are not drawn from the chain.

Tempo (BPM)

40 140

Voicing

Instrument

Sevenths

Adds the fourth chord tone. Turns a hymn into something closer to jazz without changing a single root.

Bass note

Volume (dBFS)

-36 0

Where the mix sits before the master limiter. 0 dBFS is full scale; everything starts 12 dB below it.

Entropy source

Picking a source changes the story on the receipt, never the quality: anything below class A is mixed with the OS CSPRNG before it reaches you. This result actually came from NIST Randomness Beacon.

seed token XX8DWWVG3Z8TZHVPEP2H345B4G

Re-render keeps this token. Generate replaces it. That is the whole idea.

The file is the render, sample for sample — not a second performance of it. The seed below reproduces it anywhere.

monitor

80%

This page and /api/v1/g/audio.chord run the same code. There is no private endpoint.

Chord Progressions

Result

Measurements

Seed receipt

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