# What Is Dessa AI? Block’s Voice Model Trained Only on Speech

URL: https://whatisagenticai.net/blog/what-is-dessa-ai/
Published: 2026-10-24
Publisher: Little Tough LLC, maker of AI Agent Assistant: Agentic AI (https://apps.apple.com/us/app/ai-agent-assistant-agentic-ai/id6761501260)

Dessa AI is Block’s full-duplex voice model, announced October 23, 2026 and trained only on human speech. What it is, how to try it, and if you can download it.

Dessa AI is a new voice model from Block, the company behind Square and Cash App. It went viral on October 23, 2026, mostly because of its demo clips: an AI that laughs in the middle of a sentence, gasps "oh my god" at a surprise, and talks over you the way a friend does.

If you saw "Block Dessa" in your feed and wondered what it is, whether you can use it, and why people call the voices uncanny, here is the plain-English version.

**TL;DR:** Dessa is a full-duplex, speech-to-speech AI model from a small research lab inside Block, announced on October 23, 2026. Block says it was trained from scratch only on recordings of human conversation, with no text and no pretrained models, and that it runs locally on a MacBook Pro M4 Max or better. It is a research preview: a small group of AI safety researchers gets early access, everyone else can join a waitlist, and there is no download, API or price yet.

## What is Dessa AI?

Dessa (people also type "Dessa AI," "Block Dessa" or "Dessa voice model") is an AI you talk to out loud, and it talks back out loud. Two things make it different from the voice mode in most chat apps.

**It is full-duplex.** That means it listens and speaks at the same time, like a phone call between two people. It can jump in, say "yeah" or "got it" while you are still talking, and react to how you sound, not only to what you say. Most voice assistants take turns: you talk, they wait for silence, then they answer.

**It never learned from text.** Big chatbots learn language by reading trillions of words. Block says Dessa learned only by listening to people talk. Block’s page says it is, "as far as we know," the first AI trained only on human speech that you can have a realistic live conversation with. Block also says it learned language from "hundreds of times fewer words" than large language models, without giving an exact number.

## Who made Dessa, and when did it come out?

A "(very) small AI research lab" at Block built it. The lab was founded by former members of Dessa, a Toronto deep learning startup that Block (then still called Square) bought in 2020, which is where the name comes from. The project lead is Ragavan Thurairatnam, and Block says the lab reports directly to Jack Dorsey. Block announced the model on October 23, 2026, on its site and on X.

## Dessa at a glance

| Question | Answer |
| --- | --- |
| Made by | A small AI research lab inside Block (Square, Cash App) |
| Announced | October 23, 2026 |
| Type | Full-duplex speech-to-speech model (audio in, audio out) |
| Training data | Human conversation recordings only, no text, no pretrained models |
| Training hardware | One NVIDIA GB200 NVL72 system, per Block |
| Runs on | A MacBook Pro M4 Max or better, faster than real time, per Block |
| Access | Research preview: AI safety researchers first, public waitlist |
| Download, API, price | None announced |
| Benchmarks, size, languages | Not published |

## How does Dessa work?

Most voice assistants are a relay race. One model turns your speech into text, a chatbot writes a text answer, and a third model reads it out loud. Every handoff loses something: your tone, your pauses, the laugh in your voice.

Dessa skips the relay. Sound goes in and sound comes out of one model. Block says that lets it hear and produce emotion, sarcasm, laughter and sighs. Block frames this partly as a safety issue, saying today’s AI is "nearly deaf" to the emotion in our voices.

The demos on Block’s page are live recordings with subtitles added afterward. They include Dessa laughing mid-sentence, finishing a movie title, giving gentle life advice, and even chatting with GPT-Live-1, OpenAI’s voice model. Block notes that GPT-Live-1’s maker is not affiliated with Block and has not endorsed Dessa. Gizmodo’s review of the clips called the voices uncanny and human-ish, and pointed out a guessing-game demo where Dessa kept guessing after it had already won.

## Can I use Dessa AI? Is there a download?

Not yet. Here is what is open right now:

- **Waitlist.** Anyone can join the public waitlist on Block’s Dessa page (block.xyz/dessa).

- **Safety researcher access.** A small group of AI safety researchers can apply with an institutional email to test it and find "risks we haven’t anticipated."

- **Demos.** You can listen to the recorded conversations on Block’s page and on X.

Some searches ask about a "Block Dessa download." Block says the model can run on a laptop, but it has not released weights, an app or an API, and its page says launch links are "coming soon." Be careful with any site offering a Dessa download today: there is no official one.

## Is Dessa AI free?

There is nothing to pay for yet, because there is nothing to buy. Block has not announced a price, a product or a release date, and it has not said how it plans to use Dessa, for example inside Cash App or Square.

## Dessa vs. ChatGPT voice and other voice AI

Gizmodo described ChatGPT’s voice as robotic next to Dessa in a side-by-side clip. That is one outlet’s impression of hand-picked demos, not a test. Block has published no benchmarks, so there is no fair score to compare. The bigger difference is the recipe: OpenAI’s GPT-Live models are built on top of huge text-trained models, while Dessa learned from speech alone. That is why Thurairatnam called it "a GPT3 moment for speech," per Unite.AI. Developers who need a voice agent today have shipping options instead, like [Mistral’s Voxtral 3](https://whatisagenticai.net/blog/what-is-voxtral-3/), which has an API and real prices.

## What this means for you

Dessa is a peek at where talking to AI is going: less like dictating to a machine, more like a phone call with someone who gets the joke. But a voice that sounds human does not book your trip or compare three insurance quotes. That work needs [agentic AI](https://whatisagenticai.net/what-is-agentic-ai/), models that plan steps and use tools. In **Agentic AI**, a team of expert agents takes a goal like "plan a weekend in Austin under $600" and does the research, the comparisons and the write-up on your iPhone. No model shopping, and no account needed to start.

## Quick answers

**What is Dessa AI?** Dessa is a full-duplex, speech-to-speech AI model from Block, announced October 23, 2026. It listens and talks at the same time and was trained only on recordings of human conversation.

**Who made the Dessa AI voice model?** A small research lab at Block led by Ragavan Thurairatnam, founded by former members of the Toronto startup Dessa that Block bought in 2020.

**Is there a Block Dessa download?** No. Block has not released weights, an app or an API. It says the model runs on a MacBook Pro M4 Max or better, but launch links are "coming soon."

**How do I join the Dessa AI waitlist?** Go to Block’s Dessa page at block.xyz/dessa and sign up. AI safety researchers can apply separately for early access with an institutional email.

**Is Dessa better than ChatGPT voice?** Early reviews of the demos say it sounds more human, but Block has published no benchmarks, so there is no independent comparison yet.

**Is Dessa open source?** Not as of October 24, 2026. Block has not mentioned open weights or a license.

New AI words every day, explained simply, in our [agentic AI glossary](https://whatisagenticai.net/agentic-ai-glossary/).

**Sources:** [Block: Dessa](https://block.xyz/dessa) · [Block on X (Oct 23)](https://x.com/blocks/status/2113721026324615173) · [The Verge (Oct 23)](https://www.theverge.com/ai-artificial-intelligence/1017906/jack-dorsey-block-dessa-ai-voice-speech) · [Gizmodo (Oct 24)](https://gizmodo.com/check-out-the-many-uncanny-human-ish-voices-from-blocks-new-ai-model-2000830237) · [Unite.AI (Oct 23)](https://www.unite.ai/block-unveils-dessa-a-full-duplex-speech-model-trained-on-conversation/) · [The Tribune](https://www.tribuneindia.com/news/business/jack-dorseys-block-launches-dessa-ai-voice-model-trained-entirely-on-human-conversation)