Step-Audio
Open-source end-to-end speech AI model from StepFun — real-time voice understanding, generation, and editing in a single system.
💡 In plain words
An AI system that can understand speech, generate natural-sounding voices, and edit audio expressions — all in one model. Think of it as a voice AI that can listen, respond, and adjust how it sounds, running as a single intelligent system rather than separate tools stitched together.
🎯 A real example
Feed Step-Audio a voice recording and ask it to change the emotion to excited — it edits the vocal expression while keeping the same voice and words, all processed through one unified AI model.
🤔 Is it for you?
- Developers building voice-enabled AI applications
- Researchers working on speech AI and audio models
- Projects that need real-time voice generation and editing
- You want to generate music or songs
- You need a simple GUI tool without coding
- You're looking for a consumer-ready product
What is Step-Audio?
Step-Audio is a family of open-source, end-to-end speech AI models developed by StepFun — the same Chinese AI lab behind the ACE-Step music generation model. While ACE-Step UI generates music and songs, Step-Audio focuses on speech: understanding spoken language, generating natural voices, and editing vocal expressions.
The key distinction is “end-to-end” — unlike traditional speech pipelines that chain separate recognition, processing, and synthesis steps together, Step-Audio processes audio input and produces audio output through a single unified model.
Key models
Step-Audio 2.5 Realtime is the latest flagship model, built for live voice applications. It supports fully customizable personas, Chinese and English, and connects via WebSocket API for real-time interaction.
Step-Audio-EditX is a 3-billion-parameter model specialized in expressive audio editing — changing emotion, speaking style, and paralinguistic features in existing audio while preserving the voice. Supports Japanese and Korean alongside Chinese and English.
Step-Audio-R1 is an audio reasoning model that can analyze and reason about audio content, adding intelligence beyond simple transcription and generation.
Who is Step-Audio for?
Step-Audio is a developer and researcher tool — it’s open-source code and models on GitHub, not a polished consumer app. It’s ideal for building voice-enabled AI applications, creating custom voice assistants, and research into speech AI. For music generation, use ACE-Step UI instead. For simple text-to-speech, consumer tools like TTSMaker are more accessible.
Conclusion
Step-Audio represents the speech side of StepFun’s AI ambitions. As an open-source, end-to-end speech model family, it’s a powerful foundation for developers building the next generation of voice-enabled applications.
Official resource: Step-Audio
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