Cartesia AI Secures $100M Investment to Launch Sonic-3, Pioneering Real-time Voice AI with State Space Models

Cartesia AI, a company at the forefront of voice artificial intelligence, has announced a significant funding round of $100 million. The investment, backed by prominent venture capital firms Kleiner Perkins, Index Ventures, Lightspeed, and technology giant NVIDIA, coincides with the launch of its new flagship product, Sonic-3, a state-of-the-art model for real-time conversational AI.

This latest capital infusion follows a previous $64 million Series A round in March 2025, bringing Cartesia AI's total funding to over $160 million. The substantial investment underscores growing confidence in the company's innovative approach to voice technology and its market potential. The funds are expected to accelerate research and development, expand operations, and further solidify Cartesia AI's position in the competitive AI landscape.

At the core of this announcement is Sonic-3, which promises a new era of natural and efficient AI conversations. According to Cartesia AI CEO Karan Goel, "What makes Sonic-3 great: Breakthrough naturalness - laughter and full emotional range, Lightning fast - 90ms model latency, 190ms end-to-end (fastest on market), [and it] Supports 42 languages." This technological leap aims to overcome the limitations of existing voice AI systems.

A key differentiator for Sonic-3 is its foundation in State Space Models (SSMs) rather than the widely used Transformer architecture. Goel explained the distinction, stating, "Transformers (what everyone else uses) are like rewatching the entire conversation from the start before saying each new word... SSMs (what Sonic-3 uses) are like humans, remembering the topic and vibe of the conversation. Enough context to speak naturally without replaying everything." Goel and his co-founder, Albert, pioneered the SSM paradigm at Stanford AI Lab, including models like S4 and Mamba, which are now seeing industry-wide adoption.

Cartesia AI's existing Sonic technology already powers millions of conversations monthly for thousands of businesses, including major players like ServiceNow, Cresta, and Decagon. To demonstrate confidence in Sonic-3's superior performance, Goel issued a challenge: "If you're qualified and we can't make your voice AI better than what you're using now, I'll donate $5K to your chosen charity." This bold move highlights the company's belief in its new model's capabilities and its commitment to advancing the voice AI industry.