Text-to-Speech

Text-to-speech has undergone a stunning transformation from robotic concatenation to near-human expressiveness in under five years. ElevenLabs, OpenAI's TTS, and XTTS-v2 produce speech that most listeners cannot distinguish from recordings, while open models like Bark, VALL-E (Microsoft), and F5-TTS demonstrated that voice cloning from 3-second samples is now a commodity capability. The frontier has moved beyond intelligibility (solved) to prosody, emotion control, and real-time streaming at under 200ms latency for conversational AI. Evaluation remains messy — MOS (Mean Opinion Score) is subjective and expensive, and automated metrics like UTMOS only loosely correlate with human preference, making benchmark comparisons unreliable.