Cartesia: Ultra-Fast Text-to-Speech (Sonic)

May 08, 2026

Cartesia is pushing the boundaries of what is possible with AI-generated voice. Their "Sonic" model is designed for ultra-low latency, delivering expressive, human-like speech in milliseconds, making it a perfect match for real-time conversational agents.

Human-Like Expressiveness

Sonic isn't just fast; it sounds natural. It captures the subtle prosody, emotion, and rhythm of human speech, avoiding the "robotic" tone common in older TTS systems. This expressiveness is key to building AI characters and assistants that users enjoy interacting with.

Real-Time Streaming API

Cartesia provides a robust streaming API that allows for "word-by-word" audio generation. This ensures that the AI can start speaking as soon as the first few tokens are generated by the LLM, creating a seamless, natural conversation flow that mimics human-to-human interaction.