How to Use Text to Speech

SSE is a streaming protocol where you send a single request to our API to convert text into speech. Our API will then stream the generated audio back to you in real-time, providing the lowest possible latency. Below are some examples of how to use this endpoint.

The SDK examples demonstrate how to send a message to the API, receive the audio stream from the server, and play it through your device’s speaker.

# Replace <API_KEY> with your actual API key.
# To switch languages, replace the lang_code in the path parameter (e.g., /en) with the desired language code.
curl -N --request POST \
  --url https://eu-west-1.api.neuphonic.com/sse/speak/en \
  --header 'Content-Type: application/json' \
  --header 'X-API-KEY: <API_KEY>' \
  --header 'Accept: text/event-stream' \
  --data '{
  "text": "Hello, world!"
}'

WebSockets offer a powerful way to create a two-way communication channel between your application and the server. This means you can send messages to the server and receive responses back in real-time. WebSockets are ideal for situations where you need the lowest possible latency, as they allow you to send text to the server in small, easy-to-manage pieces.

This protocol is especially useful for applications that involve continuous text streams, such as when connecting Neuphonic TTS to a language model like GPT-4o, which generates responses word by word. This setup ensures minimal latency and makes it easy to integrate with other services, as audio is streamed back to you as soon as it is generated.

Because WebSockets work by streaming data, you need to use special <STOP> tokens to tell the server when a piece of text is complete and ready to be processed. An appropriate example of when the <STOP> symbol could be used is at the end of a stream of messages output from a language model.

This is all demonstrated in the SDK examples below. They demonstrate how to send messages to the API and attach event handlers to play the received audio through your device’s speaker.

# First do `npm install -g wscat`
wscat -c "wss://eu-west-1.api.neuphonic.com/speak/en?api_key=<API_KEY>&speed=1.0&lang_code=en&sampling_rate=22050"
# And then type "Hello, World! <STOP>" and hit "Enter"

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Return Configuration

If you call the websocket directly the returned response is a JSON object with a structure that contains audio data, sampling rate, the input text and other details. Below is a breakdown of the format:

{
  "data": {
    "audio": "<audio_data_string>",
    "text": "<input_text>",
    "sampling_rate": 22050 // Default value
  }
}