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

# Hume AI

> Use the Hume AI text-to-speech plugin in a Zero Runtime pipeline.

Hume AI is a **text-to-speech** plugin. It turns the LLM's reply into expressive,
emotion-aware audio the caller hears.

## Setup

Set your Hume AI API key in the worker environment. Generate a key from the [Hume AI dashboard](https://platform.hume.ai/settings/keys):

```bash theme={null}
export HUMEAI_API_KEY=<key>
```

## Usage

Import the plugin and pass it to the pipeline's `tts` slot.

<CodeGroup>
  ```python Python theme={null}
  from zeroruntime.plugins import HumeAITTS

  tts = HumeAITTS()

  # Pipeline(tts=tts, ...)
  ```

  ```typescript Node JS theme={null}
  import { HumeAITTS } from '@zeroruntime/js-sdk/plugins';

  const tts = HumeAITTS();

  // Pipeline({ tts, ... })
  ```
</CodeGroup>

## Parameters

| Parameter | Type | Default | Description |
| - | - | - | - |
| `api_key` | `str` | `None` | Hume AI API key. Falls back to the `HUMEAI_API_KEY` environment variable when unset. |
| `voice` | `str` | `"Serene Assistant"` | Voice name or UUID. Can be a name from Hume's built-in voice library (e.g. `"Serene Assistant"`, `"Male English Actor"`), the name of a custom saved voice, or a UUID string. |
| `speed` | `float` | `1.0` | Speaking speed multiplier on a non-linear scale from `0.5` (much slower) to `2.0` (much faster), where `1.0` is normal pace. |
| `sample_rate` | `int` | `24000` | Advertised output sample rate in Hz. Hume AI's API always returns audio at 48 kHz regardless of this value. |

Spoken replies support interruptions. When the caller talks over the agent, the runtime
stops the audio and listens again. See the [plugins overview](/runtime-sdk/plugins/overview) for how
TTS fits into the rest of the pipeline.


This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.