Block, the company behind Square and Cash App, has unveiled an AI speech model called Dessa.
Block says Dessa is the first AI model trained entirely on human speech, with no text data at all, built from scratch. Instead of converting audio to text first, Dessa processes speech directly as audio. That lets it pick up on emotions, sarcasm, laughter, and pauses in real time.
The model supports full-duplex communication, so it can listen and talk at the same time. It runs locally on a MacBook Pro M4 Max and was trained on a single NVIDIA GB200 NVL72. Block says it built Dessa out of curiosity, a desire for better human-AI communication, and safety concerns, since current voice AI ignores emotional cues. Dessa isn't publicly available yet. The team is first looking for AI security researchers to test the model for unexpected risks. Anyone interested can sign up via a form.
Earlier attempts at emotional voice AI haven't stuck
Several teams have tried to build voice AI that sounds emotionally rich. In March 2024, the startup Hume AI launched EVI (Empathic Voice Interface), a voice AI with "emotional intelligence." Kyutai followed in September 2024 with Moshi. LAION's Open Empathic project has been working since late 2023 on training empathetic speech synthesis models using an open-source audio dataset. OpenAI overhauled ChatGPT's "Advanced Voice Mode" in June 2025 and has continued refining it since then, adding better intonation, pausing, and more realistic expressions of empathy and sarcasm.
But sounding emotional isn't the same as being emotional or intelligent, even if it creates that impression. For advanced speech AI, capabilities like reasoning while responding matter more than how natural the voice sounds, because they actually affect the quality of the answer.
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