StepFun releases StepAudio 3 family
Its Realtime model tops Artificial Analysis full-duplex rankings
Confirmed
The takeaway
Chinese lab StepFun launched StepAudio 3, five audio models (Realtime, ASR Max, TTS, Gen, Music).
Status
- Claim
Confirmed
- Our reporting
- High confidence
- Importance
- 3 of 5
- Last verified
- 29 September 2026
Your AI and this story
- GPT-6 Astra138 days after its cutoff
- Claude Opus 5.577 days after its cutoff
- Gemini 4 Hydrogen168 days after its cutoff
- Grok 4.7107 days after its cutoff
None of these four assistants can know about it. The closest, Claude Opus 5.5, stops 77 days before it.
Key facts
- API ids: stepaudio-3-realtime-preview, stepaudio-3-chat-preview, stepaudio-3-asr-max, stepaudio-3-tts, stepaudio-3-gen-preview, stepaudio-3-music-preview
- Realtime/Gen/Music free during preview; ASR Max $0.40/hour; TTS $0.36 per 10k characters
- Realtime runs private reasoning in parallel with speech (Think-While-Speaking); 98.9 on Artificial Analysis Full-Duplex Bench
- StepAudio 3 ASR 1.7% WER on AA-WER (StepAudio 2.5 ASR: 4.7%) per Artificial Analysis
- Follows StepAudio 2.5 Realtime (2026-05-26): persona/role-play realtime model (zh/en) with million-scale persona augmentation and role-play RLHF; project page reports 80.41 human eval, 86.36 general dialogue, 79.80 spoken QA, 82.18 paralinguistics, first on all five of StepFun’s own dimensions
What happened
StepFun released a full audio stack at once and made the Realtime, Gen and Music models free during a preview period. The Realtime model’s technical report describes a listen-converse-think-act loop with “Deep Perception”, “Seamless Duplex” and “Think-While-Speaking” components.
Why it matters
A Chinese startup’s voice model led a major independent leaderboard on conversational dynamics ahead of Western frontier-lab voice models (GPT-Live-1 per StepFun’s comparison), showing how fast full-duplex voice is commoditizing.
Leaderboard positions are as of launch and come from StepFun’s and Artificial Analysis’s X posts.
Sources
7 sources from 5 sites. Numbers match the chips in the text.
7 sources: 5 primary, 1 press, 1 reaction
Primary
- StepFun on X - Introducing StepAudio 3x.com, official
- StepFun audio models docsplatform.stepfun.ai, docs
- StepFun pricingplatform.stepfun.ai, docs
- StepAudio 3 Realtime Technical Reportarxiv.org, paper
- StepAudio 2.5 Realtime project pagestepaudiollm.github.io, official
Press
- Decrypt - StepFun’s voice AI topped every benchmark (StepAudio 2.5)decrypt.co, press
Reactions
- Artificial Analysis on X - StepAudio 3 ASR #1 on AA-WERx.com, discussion
Changes
- Added StepAudio 2.5 Realtime project page and its self-reported scores
- Filed