OpenAI

OpenAI offers versatile multilingual voices balancing low latency and good quality. While voices are optimized for English, they perform well across all supported languages.

Consult OpenAI's Text-to-Speech documentation for more information and audio samples for available voices.

Voice IDs

Copy the voice ID from OpenAI's Voice Options reference.

Prepend openai. and the string is ready for use. For example: openai.alloy

Voices

OpenAI provides 6 fully multilingual voices optimized for natural-sounding speech:

Voice	Description
alloy	Neutral, balanced voice
echo	Warm, expressive voice
fable	British accent, articulate
onyx	Deep, authoritative voice
nova	Energetic, friendly voice
shimmer	Soft, gentle voice

Models

OpenAI offers two TTS models with different quality and latency characteristics:

Model	Description
tts-1	Default - Standard quality, optimized for speed
tts-1-hd	High-definition quality, improved audio fidelity

Voice IDs

OpenAI voice IDs conform to the following format:

openai.<voice>:<model>

Parameters:

• voice (required): One of: alloy, echo, fable, onyx, nova, shimmer
• model (optional): tts-1 (default) or tts-1-hd

Examples:

openai.alloy
openai.nova:tts-1-hd
openai.fable:tts-1

Languages

All OpenAI voices are fully multilingual and automatically adapt to the input text language.

Consult OpenAI's supported languages resource for an up-to-date list.

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Examples

Learn how to use OpenAI voices on the SignalWire platform.

SWML

Use the languages SWML method to set one or more voices for an AI agent.

version: 1.0.0
sections:
  main:
  - ai:
      prompt:
        text: Have an open-ended conversation about flowers.
      languages:
        - name: English
          code: en-US
          voice: openai.alloy

Alternatively, use the say_voice parameter of the play SWML method to select a voice for basic TTS.

version: 1.0.0
sections:
  main:
  - set:
      say_voice: "openai.alloy"
  - play: "say:Greetings. This is the Alloy voice from OpenAI's text-to-speech model."

RELAY Realtime SDK

// This example uses the Node.js SDK for SignalWire's RELAY Realtime API.
const playback = await call.playTTS({ 
    text: "Greetings. This is the Alloy voice from OpenAI's text-to-speech model.",
    voice: "openai.alloy",
});
await playback.ended();

Call Flow Builder

OpenAI voices are not yet supported in Call Flow Builder.

cXML

<?xml version="1.0" encoding="UTF-8"?>
<Response>
<Say voice="openai.alloy">
    Greetings. This is the Alloy voice from OpenAI's text-to-speech model.
</Say>
</Response>