Speech synthesis (text-to-speech or TTS) is the AI task of generating natural-sounding spoken audio from text input. Modern TTS systems use deep learning models — often based on transformers or diffusion models — to produce speech that is nearly indistinguishable from human voice. Applications include virtual assistants, audiobook narration, accessibility tools for visually impaired users, customer service phone systems, and content localization. ElevenLabs, OpenAI's TTS, and Bark are prominent examples.