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

# TTS Streaming

> Learn about TTS streaming in Voice Gateway for real-time text-to-speech audio delivery, enabling natural voice agent conversations with minimal latency.

<a href="/release-notes/2026.14"><Badge className="version-badge" color="blue">Updated in 2026.14</Badge></a>

The *TTS Streaming* feature delivers synthesized speech to your voice AI Agent as it's generated, rather than waiting for the entire response to finish processing. This feature enables faster, more natural-sounding conversations.

Standard TTS systems wait for the entire text to be processed before playing any audio, which introduces a noticeable delay, especially with longer texts. TTS streaming instead processes text in segments and plays each one back as soon as it's synthesized.

<div style={{textAlign: 'center'}}>
  <video width="650" height="400" controls autoPlay title="Streaming vs. standard TTS" alt="A video comparing standard text-to-speech processing, which waits for the full text before generating audio, with streaming text-to-speech, which begins playback as segments are synthesized." style={{border: '1px solid #ccc', borderRadius: '12px', display: 'block', margin: '0 auto'}}>
    <source src="https://docscognigyassets.blob.core.windows.net/assets/traditional-tts-vs-tts-streaming.mp4" />
  </video>
</div>

<Note>
  Some speech providers use `streaming` to describe their API's connection method, for example, a websocket-based API for submitting multiple texts. This concept is different from TTS streaming in Voice Gateway, which refers to audio playout: how quickly synthesized audio starts playing back to the caller.
</Note>

## Key Benefits

* **Lower response latency.** Audio playback starts as soon as the first words are synthesized, instead of after the full text is processed.
* **More natural conversation flow.** Reduced time-to-first-audio makes voice AI Agent responses feel closer to real-time human conversation, especially with longer text.

## Prerequisites

* A [voice AI Agent](/ai/agents/develop/voice) configured.
* A [speech service](/voice-gateway/webapp/speech-services) configured in the Voice Gateway Self-Service Portal.

## Restrictions

* The following speech providers don't support TTS Streaming: AWS, Google, Nuance, Speechmatics, and Deepgram Flux.
* [TTS vendor fallback](/voice-gateway/webapp/applications#add-additional-tts-and-stt-vendor) doesn't work with TTS Streaming. If TTS streaming is activated, the fallback vendor configuration is ignored.
* For ElevenLabs, Voice Gateway uses the [ElevenLabs streaming API](https://elevenlabs.io/docs/api-reference/text-to-speech/stream). The following parameters aren't supported and can't be specified in **Extra Options**:
  * `seed`
  * `previous_request_ids`
  * `next_request_ids`
  * `apply_text_normalization`
  * `apply_language_text_normalization`
  * `use_pvc_as_ivc`
  * `pronunciation_dictionary_locators`

## How to Configure TTS Streaming

To activate streaming for your voice AI Agent, follow these steps:

<AccordionGroup>
  <Accordion title="1. Configure Speech Service in Voice Gateway Self-Service Portal">
    1. In the navigation menu of the Voice Gateway Self-Service Portal, select **Speech**.
    2. On the **Speech services** page, select an existing speech service or [create a new one](/voice-gateway/webapp/speech-services) by clicking **Add a speech service** in the upper-right corner.
    3. On the **Add Speech service** page, make sure that the **Use for text-to-speech** option is activated.
    4. Activate the **Enable text-to-speech streaming** option.
    5. *(Optional)* For ElevenLabs, configure the **Extra Options** field to customize the TTS streaming behavior. See the list of unsupported parameters in the [Restrictions](#restrictions) section.
    6. Click **Save**.
  </Accordion>

  <Accordion title="2. Configure the Set Session Config Node in Cognigy.AI">
    1. Go to the Set Session Config Node in your Flow.
    2. In the **Synthesizer (TTS)** section, select your speech service from the **TTS Vendor** list.
    3. Configure **TTS Language** and **TTS Voice** as needed.
  </Accordion>
</AccordionGroup>

## More Information

* [Speech Services](/voice-gateway/webapp/speech-services)
* [TTS and STT vendors](/voice-gateway/references/tts-and-stt-vendors)