Block releases Dessa, a speech-to-speech model trained only on human conversation
AspireAI · Block
Block trained an AI on nothing but human voices, and the result can talk over you.
Dessa is a full-duplex speech model from Block's AI lab: audio in, audio out, no text in the middle. It listens while it speaks, backchannels with "yeah" and "got it", and picks its own moments to laugh mid-sentence.
It works like a phone call rather than a walkie-talkie. Most voice AI flattens speech into text, then reads a reply back. Dessa was trained from scratch on human conversation only, so it picked up timing and tone from people rather than from written words.
The honest limitation: it is not available. Block is giving early access to a small group of AI safety researchers first, and Block's own demo clips include awkward moments, like mistaking the speaker for "Ronaldo."
https://block.xyz/dessa
Read the story and explore more from the AspireAI community.
Two sparse-autoencoder analyses have resisted scaling: matching semantically similar features across layers, and compressing large feature circuits into interpretable supernodes. This paper argues both are the same underlying problem, estimating semantic distances between SAE features that sit on different activation manifolds. Its representation treats each feature not as a single decoder vector but as an activation-weighted distribution over the hidden states expressing it, projects those distributions into a shared reference space, and compares them with Wasserstein distance. The representation is proved invariant to activation rescaling and stable under perturbation, and recovers true matches under finite-sample margin conditions. Empirically it outperformed decoder-vector and LLM-based baselines and captured subtle functional distinctions between related features, and it compressed large feature circuits into interpretable supernodes automatically. The limitation is that this is interpretability tooling: the paper demonstrates better feature matching and circuit compression, not that downstream interpretability claims become more accurate.