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

# Using synthesizers

> How to control the voice of your application.

# Overview

Synthesizers are used to convert text into speech; this guide will show you how to configure and use synthesizers in Vocode.

## Supported Synthesizers

Vocode currently supports the following synthesizers:

1. Azure (Microsoft)
2. Google
3. Eleven Labs
4. Rime
5. Play.ht
6. Coqui TTS
7. GTTS (Google Text-to-Speech)
8. Stream Elements
9. Bark

These synthesizers are defined using their respective configuration classes, which are subclasses of the `SynthesizerConfig` class.

# Configuring Synthesizers

To use a synthesizer, you need to create a configuration object for the synthesizer you want to use. Here are some examples of how to create configuration objects for different synthesizers:

### Example 1: Using Eleven Labs with a phone call

```python theme={null}
from vocode.streaming.telephony.hosted.inbound_call_server import InboundCallServer
from vocode.streaming.models.synthesizer import ElevenLabsSynthesizerConfig

server = InboundCallServer(
    ...
    synthesizer_config=ElevenLabsSynthesizerConfig.from_telephone_output_device(
        api_key=os.getenv("ELEVENLABS_API_KEY"),
        voice_id=os.getenv("YOUR VOICE ID")
    )
    ...
)
```

In this example, the `ElevenLabsSynthesizerConfig.from_telephone_output_device()` method is used to create a configuration object for the Eleven Labs synthesizer.
The method hardcodes some values like the `sampling_rate` and `audio_encoding` for compatibility with telephone output devices.

### Example 2: Using Azure in StreamingConversation locally

```python theme={null}
from vocode.streaming.models.synthesizer import AzureSynthesizerConfig
from vocode.helpers import create_microphone_input_and_speaker_output

microphone_input, speaker_output = create_microphone_input_and_speaker_output(
        streaming=True, use_default_devices=False
)

conversation = StreamingConversation(
    ...
    synthesizer=AzureSynthesizer(
        AzureSynthesizerConfig.from_output_device(speaker_output)
    ),
    ...
)
```

In this example, the `AzureSynthesizerConfig.from_output_device()` method is used to create a configuration object for the Azure synthesizer.
The method takes a `speaker_output` object as an argument, and extracts the `sampling_rate` and `audio_encoding` from the output device.

## When to Use Configs vs. Synthesizer Objects

* For everything except `StreamingConversation`, you must use configuration objects.
* For `StreamingConversation`, you can use the actual synthesizer object, but you still need to initialize it with a configuration object.

## Synthesizer Comparisons

| Provider          | Latency | Voice Cloning | Natural Sounding | Notes       |
| ----------------- | ------- | ------------- | ---------------- | ----------- |
| Azure (Microsoft) | Low     | No            |                  |             |
| Google            | Low     | No            |                  |             |
| Eleven Labs       | High    | Yes           |                  |             |
| Rime              | Low     | No            |                  |             |
| Play.ht           | High    | Yes           |                  |             |
| Coqui TTS         |         |               |                  | Open source |
| GTTS              |         |               |                  |             |
| Stream Elements   |         |               |                  |             |
| Bark              |         |               |                  |             |