Cartesia Raises $100 Million to Transform Real-Time Voice AI with Sonic-3

Silicon Valley startup Cartesia has secured a $100 million funding round from Kleiner Perkins, Index Ventures, Lightspeed, and NVIDIA. Co-founded by Stanford AI Lab alumni Karan Goel and Albert Gu, Cartesia is launching Sonic-3, a real-time conversational AI model.

Sonic-3 redefines what’s possible in voice AI by delivering a combination of uniqueness, speed, and multilingual support. It captures the full emotional range of human speech, including laughter, tone variation, and subtle emotional shifts, making conversations feel deeply authentic and engaging.

It also boasts lightning-fast performance, with a model latency of just 90 milliseconds and a total end-to-end response time of 190 milliseconds, placing it among the fastest real-time voice AI systems available. Its global reach is equally impressive, supporting 42 languages, enabling enterprises to deploy truly global, natural voice applications that meet diverse market needs.

Unlike most voice AI solutions that rely on Transformer architectures, Sonic-3 is built on State Space Models (SSMs). The traditional Transformer-based models process conversations by re-reviewing all preceding dialogue to predict each next word, similar to replaying the entire conversation repeatedly. This approach introduces latency and inefficiency.