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

# NaturalHD

> Telnyx NaturalHD is a high-fidelity multilingual text-to-speech model backed by Rime Arcana, offering studio-quality voices for premium voice applications.

**Voice format:** `Telnyx.NaturalHD.<voice>`

Pre-built voices backed by Rime Arcana. 9 languages: en, fr, de, es, ar, hi, ja, he, pt.

## Voice Samples

| Voice                       | Language | Gender | Sample                                                                    |
| --------------------------- | -------- | ------ | ------------------------------------------------------------------------- |
| `Telnyx.NaturalHD.astra`    | en-US    | Female | <audio controls src="/audio/tts-samples/telnyx-naturalhd-astra.mp3" />    |
| `Telnyx.NaturalHD.albion`   | en-US    | Male   | <audio controls src="/audio/tts-samples/telnyx-naturalhd-albion.mp3" />   |
| `Telnyx.NaturalHD.amarante` | fr-FR    | Female | <audio controls src="/audio/tts-samples/telnyx-naturalhd-amarante.mp3" /> |
| `Telnyx.NaturalHD.luna`     | en-US    | Female | <audio controls src="/audio/tts-samples/telnyx-naturalhd-luna.mp3" />     |

***

## WebSocket

### Query Parameters

```
wss://api.telnyx.com/v2/text-to-speech/speech?voice=Telnyx.NaturalHD.astra&audio_format=mp3
```

| Parameter      | Type    | Default | Description                                     |
| -------------- | ------- | ------- | ----------------------------------------------- |
| `audio_format` | string  | `mp3`   | `mp3`, `linear16`.                              |
| `sample_rate`  | integer | `24000` | 8000, 16000, 22050, 24000, 44100, 48000, 96000. |

### Voice Settings

Send in the init frame (`{"text": " "}`):

| Field         | Type  | Default | Description             |
| ------------- | ----- | ------- | ----------------------- |
| `voice_speed` | float | `1.0`   | Speech rate multiplier. |

```json theme={null}
{
  "text": " ",
  "voice_settings": {
    "voice_speed": 0.9
  }
}
```

## REST API

### Fields

| Field         | Type   | Default         | Description                                      |
| ------------- | ------ | --------------- | ------------------------------------------------ |
| `voice_speed` | float  | `1.0`           | Speech rate multiplier.                          |
| `output_type` | string | `binary_output` | `binary_output`, `base64_output`, or `audio_id`. |

### Response

Default (`binary_output`): chunked audio bytes with `Content-Type: audio/mpeg` (or `audio/wav`, `audio/pcm`).

With `output_type: "base64_output"`: JSON with base64-encoded audio.

With `output_type: "audio_id"`: JSON with an `audio_url` for deferred retrieval.