> ## Documentation Index
> Fetch the complete documentation index at: https://docs.voicemark.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Cloud VoiceMark

> A live acoustic fingerprint of a single utterance.

The **Cloud VoiceMark** is a per-utterance acoustic portrait. It captures the word-level f0, energy, and spectral shape of one specific recording. It changes every time the same person speaks.

## What it represents

* A live signal that this person **spoke right now**
* Useful as a visual liveness confirmation in your UI
* Detects synthetic or cloned audio — TTS shows flat f0 and uniform spectral bands

## Where it comes from

The Cloud VoiceMark data is returned by `/v1/verify` inside `cloud_data.words`:

```json theme={null}
{
  "cloud_data": {
    "words": [
      { "word": "Wild", "f0": 142.3, "rms": 0.08, "bands": [0.4, 0.6, 0.3, 0.2] },
      { "word": "roses", "f0": 128.1, "rms": 0.11, "bands": [0.5, 0.7, 0.4, 0.3] },
      ...
    ],
    "glyph_params": { ... }
  }
}
```

## Word-level fields

| Field | Type | Description |
| - | - | - |
| `word` | string | Transcribed word |
| `f0` | number | Fundamental frequency (Hz). Real speech: 80–300 Hz. TTS: often flat or zero. |
| `rms` | number | Root mean square energy (0–1). Indicates emphasis and projection. |
| `bands` | number\[4] | Spectral energy in four sub-bands. Use to colour-map word clouds. |

## Rendering guidance

Use `f0` to size or weight each word in a phrase cloud — louder, more stressed words render larger. Map `bands[0]` (low) → warm colours, `bands[3]` (high) → cool colours. The variation across words signals authentic human speech.

> [!TIP]
>
> The `liveness_score` in the verify response encodes the f0 variation analysis. If you only need the score and not the raw data, use that field.


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