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

# Synthesizer

> Use voice stability, voice similarity, and speaking rate to shape how your AI voice sounds.

With **synthesizer settings**, you can directly shape your assistant's voice. You mainly work with three sliders:

* **Voice stability**
* **Voice similarity**
* **Speaking rate**

<div style={{ position: "relative", paddingBottom: "56.25%", height: 0 }}>
  <iframe style={{ position: "absolute", top: 0, left: 0, width: "100%", height: "100%", border: 0 }} src="https://www.tella.tv/video/vid_cmn3023y801bo07m82kvr3xku/embed?b=0&title=0&a=1&loop=0&t=0&muted=0&wt=0&o=1" allowFullScreen allowTransparency />
</div>

## 1. Voice stability

**Voice stability** controls how monotone vs. expressive the voice sounds.

* **More to the right**: steadier, more formal, more consistent.
* **More to the left**: more emotional, friendlier, more dynamic.

A common starting point is around **0.30**, but the right value depends on your use case.

## 2. Voice similarity

**Voice similarity** is a fine-tuning control for stability and closeness to the chosen base voice.

If you want an emotional voice to keep that character more consistently, or stay closer to the original reference voice, move this slider further right.

## 3. Speaking rate

**Speaking rate** depends heavily on the selected voice.

* **1.0** is often a good baseline.
* Some voices are naturally slower or faster, so tune accordingly.

## Recommended workflow

1. Pick your voice first.
2. Start with moderate default values.
3. Change only **one** slider per test.
4. Listen, compare, then continue.

This gets you to a stable voice setup faster for your real scenario.

<Tip>
  Results are voice-specific. Test with realistic phrases from your real call flow, not only short demo sentences.

  Continue with: [TTS providers](/en/platform/tts-providers), [Voice selection](/en/ai-assistants/voice-selection), and [Testing](/en/ai-assistants/testing).
</Tip>