OpenAI Text-to-Speech (TTS)

OpenAI's Text-to-Speech API converts text into natural-sounding spoken audio. It offers multiple voice options, two quality tiers, and supports various output formats. TTS is useful for building voice assistants, accessibility features, audio content, and narration tools.

Available Models

• tts-1: Optimized for low latency, suitable for real-time applications
• tts-1-hd: Higher quality audio, best for pre-generated content

Voices

OpenAI provides six built-in voices: alloy, echo, fable, onyx, nova, and shimmer. Each has a distinct tone and character.

Getting Started

import OpenAI from 'openai';
import fs from 'fs';

const openai = new OpenAI();

const response = await openai.audio.speech.create({
  model: 'tts-1',
  voice: 'alloy',
  input: 'Hello! Welcome to our application.',
});

// Save to file
const buffer = Buffer.from(await response.arrayBuffer());
fs.writeFileSync('output.mp3', buffer);

Streaming Audio in a Next.js API Route

// app/api/tts/route.ts
import OpenAI from 'openai';

const openai = new OpenAI();

export async function POST(req: Request) {
  const { text, voice = 'alloy' } = await req.json();

  const response = await openai.audio.speech.create({
    model: 'tts-1',
    voice,
    input: text,
    response_format: 'mp3',
  });

  return new Response(response.body, {
    headers: {
      'Content-Type': 'audio/mpeg',
    },
  });
}

Output Formats

Use Cases

• Accessibility: Read content aloud for visually impaired users
• Voice assistants: Speak AI responses in chat applications
• Audio content: Generate podcasts, audiobooks, or narration
• Language learning: Pronounce words and phrases for learners
• Notifications: Audio alerts and announcements

Best Practices

• Use tts-1 for real-time applications where speed matters
• Use tts-1-hd for pre-generated content where quality is the priority
• Test all six voices to find the best match for your application's tone
• Cache generated audio for frequently used phrases to reduce API calls

Resources

• OpenAI TTS Guide
• TTS API Reference