Jack Dorsey's Block has announced Dessa, a voice artificial intelligence model trained on human conversation, sharing recordings that invite listeners to hear exchanges ranging from natural banter to awkward misunderstandings. The company says Dessa learned to hold conversations from audio alone, without text or pretrained models. It describes the system as a speech-to-speech model whose knowledge comes entirely from human speech.
Block argues that voice systems which convert speech into text discard information about emotion, timing and delivery. Dessa is designed to preserve those elements, allowing conversations with pauses, changes in volume and laughter that can begin before a speaker finishes talking.
We believe voice is the most natural way to interact with intelligence, so we created Dessa, the most authentic full-duplex speech model ever built. Talking with it feels like talking with a person…full of emotion, nuance, pauses, and a natural cadence. https://t.co/r0qFLdvd6c
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— jack (@jack) October 23, 2026
The team describes Dessa as a full-duplex model, capable of the overlapping interaction that characterises human conversation. According to its website, the model decides what to say, when to speak and how to sound, including its voice and personality.
We made the first AI model you can have a realistic conversation with that was trained entirely on speech! Dessa is a full-duplex speech-to-speech model that you can run on consumer GPUs. This is a GPT3 moment for speech. https://t.co/XVD8sSyJn8
— Ragavan Thurairatnam (@RagavanThurair) October 23, 2026
Film Chatter, Paris Plans And A Mistaken Identity
The demonstrations also reveal some unusual moments. In a recording shared by Dessa lead Ragavan Thurairatnam, the model initially mistakes its conversation partner for someone named Ronaldo, despite otherwise maintaining a mostly natural exchange.
Other examples include a discussion of Christopher Nolan's films that veers into an unexpected tangent about Bryan Singer's Superman films. In another recording, a person tells Dessa about a surprise trip to Paris, prompting a response the team describes as sounding tearfully grateful.
The website features a conversation between Dessa and OpenAI's GPT-Live-1 voice model.
Block says the clips are live recordings without anyone steering the model. Subtitles were added afterwards. The team also says Dessa can increase its volume when asked to speak up, a behaviour it says was not explicitly taught.
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Learning To Listen, With Safety
The project's stated motivations are curiosity, improving understanding between humans and AI, and safety. Its developers point to babies learning to speak without reading as an inspiration for testing whether a model could learn through listening alone.
Meet Dessa, our AI model trained from scratch on nothing but speech. We believe speech is the natural interface for technology. So we built Dessa. And we're inviting AI safety researchers to explore Dessa. Learn more: https://t.co/6wA8KhWdjn https://t.co/vXM43uUFzx
— Ragavan Thurairatnam (@RagavanThurair) October 23, 2026
They also argue that an AI system's inability to recognise distress in someone's voice could create safety problems, particularly as such systems gain more power and independence. Dessa can run locally on a MacBook Pro with an M4 Max chip or better, according to the team.
Block says a small group of AI safety researchers will receive early access. The team has also raised research questions about how speech-trained models acquire facts and languages, and how they learn from information provided during conversations. It presents those questions as areas for investigation into the model's capabilities.
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