Text-to-Speech & Realtime Voice

Generating Speech

The gpt-4o-mini-tts model generates natural-sounding speech with unprecedented control over tone, emotion, and delivery style.

const audio = await openai.audio.speech.create({
  model: "gpt-4o-mini-tts",
  voice: "coral",
  input: "Welcome to the Infinity Tech Stack Academy!",
  instructions: "Speak with enthusiasm and energy, like a tech conference host.",
  response_format: "mp3"
});

Steerable TTS

Unlike traditional TTS that just reads text flatly, gpt-4o-mini-tts accepts instructions that control HOW it speaks — tone, pacing, emotion, accent emphasis.

Available Voices

The Realtime API

For ultra-low latency voice applications, the Realtime API maintains a persistent WebSocket connection for bidirectional audio streaming with gpt-realtime-1.5.

• Voice Activity Detection (VAD): Automatically detects when users stop speaking
• Tool Calling in Voice: Trigger backend tools while speaking
• Audio Reasoning: Understands tone, inflection, and urgency