# Noise Colours — Randomly

> White, pink, brown, blue, violet — and perceptually flat grey. One of 63 generators at [Randomly](https://randomly.cluxnei.dev), a library of random generators seeded from verifiable real-world entropy. Free HTTP API, no key, no signup.

## `audio.noise` — Noise Colours

White, pink, brown, blue, violet — and perceptually flat grey.

| | |
|---|---|
| **Key** | `audio.noise` |
| **Module** | `audio` |
| **Version** | `1` — a permalink carries this, and a replay against a different version returns `409` rather than something else |
| **Formats** | `application/json`, `text/plain`, `audio/wav` |
| **Studio** | https://randomly.cluxnei.dev/g/audio/noise |
| **API** | `GET https://randomly.cluxnei.dev/api/v1/g/audio.noise` |

`value` is a **score** — events, envelopes and synthesis parameters — not samples. Ask for `format=wav` to get the audio.

| Parameter | Type | Default | Accepts | What it does |
|---|---|---|---|---|
| `colour` | enum | `pink` | `white`, `pink`, `brown`, `blue`, `violet`, `grey` | Colour — A colour is a spectral slope. The measured slope is printed under the waveform. |
| `duration` | float | `10` | `2` – `30` | Length (seconds) — Kept short on purpose — with Loop on, the buffer is crossfaded into itself and plays forever. |
| `loop` | bool | `true` | `true`, `false` | Loop — Seamless: the tail is crossfaded onto the head, so there is no click at the seam. |
| `filter` | enum | `none` | `none`, `lowpass`, `highpass`, `bandpass` | Filter |
| `cutoff` | float | `1200` | `60` – `16000` | Cutoff (Hz) |
| `resonance` | float | `0.7` | `0.4` – `8` | Resonance (Q) — Above about 4 the filter starts to ring, which turns noise into a pitch. |
| `movement` | float | `0.3` | `0` – `1` | Movement — How far the cutoff drifts over the loop. A little of this is the difference between a hiss and something that sounds like weather. |
| `volume` | float | `-12` | `-36` – `0` | Volume (dBFS) — Where the mix sits before the master limiter. 0 dBFS is full scale; everything starts 12 dB below it. |

Out-of-range numbers are **clamped, not rejected**, so a request never fails for being
ambitious — but it may not do what you meant. Unknown keys are dropped and missing ones
fall back to the defaults above.

```bash
curl -s 'https://randomly.cluxnei.dev/api/v1/g/audio.noise?colour=pink&duration=10&loop=1' -H 'Accept: text/plain'
curl -o out.wav 'https://randomly.cluxnei.dev/api/v1/g/audio.noise?colour=pink&duration=10&loop=1&format=wav'
```

## The receipt

Every result carries one, naming the physical source of the randomness and linking to the
third party's own record of it:

```json
"receipt": {
  "source": "seismic",
  "source_label": "USGS Seismic Feed",
  "class": "C",
  "caveat": "Carries only tens of bits of genuine surprise. Always mixed with the OS CSPRNG.",
  "narrative": "A magnitude 3.6 earthquake, 67 km N of Culebra, Puerto Rico, 39.6 km down — 52 minutes ago.",
  "proof_url": "https://earthquake.usgs.gov/earthquakes/eventpage/us7000th33",
  "mixed_with_csprng": true,
  "degraded": false
}
```

Pick the source with `?source=`, or leave it at the default `auto`:

- **Class A** (Cryptographic) — `csprng`, `anu-qrng`, `random-org`
- **Class B** (Public beacon) — `nist-beacon`, `drand`, `bitcoin`. Published openly — anyone can look this value up after the fact.
- **Class C** (Observational) — `seismic`, `space-weather`, `atmosphere`, `iss`. Carries only tens of bits of genuine surprise. Always mixed with the OS CSPRNG.

## More

- [The full API contract](https://randomly.cluxnei.dev/api.md)
- [Everything in one file](https://randomly.cluxnei.dev/llms-full.txt)
- [The catalogue as JSON](https://randomly.cluxnei.dev/api/v1/generators)
- [This generator in the browser](https://randomly.cluxnei.dev/g/audio/noise)