StepFun

Step Audio 2

StepFun’s end-to-end speech model — TTS, STT and voice chat in a single checkpoint.

#22released Sep 24, 2026·Proprietary·Not disclosed
textaudio64K ctx
Intelligence
89.0 #22
AAQI 89.0
Output Speed
150 t/s
ITL 6.7 ms/tok
Blended price (3:1)
$0.015 /1M
In $0.012/M · Out $0.024/M
Context
64K
≈ 160 A4 pages · max out 8,192

Quality Domain Radar

6-Axis Frontier Evaluation vs Category Average & Flagship

Step Audio 2
Claude Mythos Preview (#1)
Average (68)
Coding (15)Mathematics (15)Hard Science (GPQA) (32)Agentic & Tool Use (55)Knowledge (MMLU) (46)Vision / Multimodal (85)

Radar axes are approximated from category scores where direct benchmark measurements are missing — see Methodology.

Strengths & Trade-offs

Where it wins

  • Single model replaces a whole voice pipeline
  • Best-in-class Chinese speech quality
  • Understands tone and emotion, not just words

Trade-offs to watch

  • English prosody below Eleven/Cartesia tiers
  • Ecosystem concentrated in APAC
  • No self-hosting

Killer Use Cases

Speech-to-speech agents
Direct voice chat without TTS/STT glue.
Chinese voice products
Native Mandarin/Cantonese synthesis and ASR.
Emotion-aware bots
Reacts to caller sentiment in real time.

Developer Quickstart & API

Set STEPFUN_API_KEY first — get an API key
curl https://api.stepfun.com/v1/chat/completions \
  -H "Authorization: Bearer $STEPFUN_API_KEY" \
  -H "content-type: application/json" \
  -d '{
    "model": "step-audio-2",
    "messages": [{"role": "user", "content": "Refactor this function for O(n) time and explain the change."}]
  }'

Official Resources & Links

API deployment

Compare hosts & latency

Throughput, TTFT and cache pricing across Groq, Cerebras, Together, DeepInfra, Fireworks, Bedrock and Azure.

GroqCerebrasTogether AIDeepInfraFireworks AIAWS BedrockAzure AI
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Scores by Source

Head-to-head Live Matchups

Live Specs & Architecture

Under the hood
Step Audio 2 — unified speech model
  • One checkpoint for TTS, STT and speech-to-speech chat
  • Paralinguistic understanding — emotion, emphasis, age cues
  • Voice-to-voice tool calling for agent stacks
  • Strong Mandarin/Cantonese coverage
Release date
Sep 24, 2026
Architecture
Step Audio 2 — unified speech model
Parameters
Not disclosed
License
Proprietary
Context Window
64,000 tokens
Max Output
8,192 tokens
Modalities
text + audio
Cache Pricing
read $0.004 · write $0.015 /1M
Reasoning
—
Input Price
$0.012/M
Output Price
$0.024/M
Output Speed
150 t/s
Time to First Token
—
Data Updated
Oct 22, 2026

Estimated monthly bill

Estimated monthly spend
$0.00
Calculating savings vs GPT-4o...

Cite & embed

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BibTeX
@misc{llmpodium2026stepaudio2,
  title = {Benchmark Analysis and Intelligence Evaluation of Step Audio 2},
  author = {LLMPodium Research},
  year = {2026},
  url = {https://llmpodium.com/models/step-audio-2}
}

Embed Score Badge

Add a live Podium Score badge to your GitHub or Hugging Face README — it links back to the live ranking.

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Step Audio 2 LLMPodium Score
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