Alexandre Défossez is Co-Founder and Chief Scientist at Gradium, a Paris-based voice AI company building foundational audio language models for real-time speech generation, transcription, and voice cloning.

Alexandre studied at the Ecole Normale Superieure and spent three years as a Research Scientist at Meta's FAIR Labs in Paris, where he led efforts in music generation and audio AI research.

At Meta, Alexandre created widely adopted open-source tools including Demucs, the Sony 2021 MDX challenge-winning music source separation model, and EnCodec, a state-of-the-art neural audio codec that became a foundational building block across the voice AI industry.

Before co-founding Gradium in September 2025, Alexandre was also a founding research team member at Kyutai, the Paris-based non-profit AI lab, where he co-authored the Moshi speech-text foundation model for real-time dialogue.

Gradium raised over $100M in seed funding backed by Nvidia, FirstMark, Eurazeo, Eric Schmidt, and Yann LeCun, and within months of launch secured enterprise customers including Renault, serving sectors from healthcare to gaming.