> ## Documentation Index
> Fetch the complete documentation index at: https://assemblyai.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# Model selection
The `speech_model` connection parameter lets you specify which model to use for streaming transcription. It's optional; if omitted, the session defaults to `u3-rt-pro`.
## Available models
| Name | Parameter | Description | Best for |
| --------------------------------------------------------------------------------- | ------------------------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------- |
| **Universal-3-5 Pro Streaming** Recommended | `"universal-3-5-pro"` | The next generation of our flagship streaming model. More languages, improved prompting, and enhanced conversational context features. | Real-time voice agents needing the latest accuracy, broad language support, and conversational context. |
| **Universal-3 Pro Streaming** | `"u3-rt-pro"` | The most accurate model with the fastest word emissions for voice agents that demand the highest quality. Best-in-class accuracy with advanced prompting capabilities. | Real-time voice agents needing premium accuracy, elite entity accuracy, IVR replacement, agent assist, multilingual code-switching |
| **Universal-Streaming English** | `"universal-streaming-english"` | An English transcription model offering a good balance of speed and cost-effectiveness. | Cost-effective English real-time transcription, English-only real-time apps |
| **Universal-Streaming Multilingual** | `"universal-streaming-multilingual"` | A multilingual transcription model offering a good balance of speed and cost-effectiveness. | Cost-effective multilingual streaming across EN/ES/DE/FR/PT/IT |
## Choosing a model
| Feature | Universal-3-5 Pro Streaming Recommended | Universal-3 Pro Streaming | Universal-Streaming English | Universal-Streaming Multilingual |
| ------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------- | ----------------------------------------------------------------------- |
| **Latency** | Fastest | Fast | Fast | Fast |
| **Supported languages** | EN, ES, DE, FR, PT, IT, TR, NL, SV, NO, DA, FI, HI, VI, AR, HE, JA, ZH | EN, ES, DE, FR, PT, IT | EN | EN, ES, DE, FR, PT, IT |
| **Partial transcripts** | Yes | Yes | Yes | Yes |
| **Multilingual** | Native Code Switching | Native Code Switching | No | Per Turn |
| **Entity accuracy** | Best | Best | Okay | Okay |
| **Disfluencies & filler words** | Yes | Yes | No | No |
| **Language detection** | Yes | Yes | No | Yes |
| **Non-speech tags** | No | No | No | No |
| **Customization** | [Keyterms prompting](/streaming/prompting-and-keyterms) (known context) + [Native prompting](/streaming/prompting-and-keyterms) (unknown context) | [Keyterms prompting](/streaming/prompting-and-keyterms) (known context) + [Native prompting](/streaming/prompting-and-keyterms) (unknown context) | [Keyterms prompting](/streaming/prompting-and-keyterms) (known context) | [Keyterms prompting](/streaming/prompting-and-keyterms) (known context) |
For detailed setup and configuration of Universal-3 Pro streaming, see the [Universal-3 Pro Streaming](/streaming/getting-started/transcribe-streaming-audio) page. For prompting guidance, see the [Prompting guide](/streaming/prompting-and-keyterms).
## Set the model
Set the `speech_model` connection parameter when you open the WebSocket.
```python theme={null}
CONNECTION_PARAMS = {
"sample_rate": 16000,
"speech_model": "universal-3-5-pro", # universal-streaming-english | universal-streaming-multilingual
}
```
```python theme={null}
client.connect(
StreamingParameters(
sample_rate=16000,
speech_model="universal-3-5-pro", # universal-streaming-english | universal-streaming-multilingual
)
)
```
```javascript theme={null}
const CONNECTION_PARAMS = {
sample_rate: 16000,
speech_model: "universal-3-5-pro", // universal-streaming-english | universal-streaming-multilingual
};
```
```javascript theme={null}
const transcriber = client.streaming.transcriber({
sampleRate: 16_000,
speechModel: "universal-3-5-pro", // universal-streaming-english | universal-streaming-multilingual
});
```