Power best-in-class voice agents
Ultra-fast and ultra-accurate streaming STT built for voice agents. Get 300ms immutable transcripts and intelligent endpointing so your agents feel more natural and finish tasks successfully.
Hello! This is an AI voice agent built with AssemblyAI's streaming speech-to-text. Ask questions about our products, APIs, and documentation to experience real-time Voice AI in action.
Please note: This agent provides customer support for AssemblyAI products only. Do not share sensitive or non-public information.
It all starts by what your agent hears
From first hello to final answer, conversations just flow—fast, accurate, and natural.
Build voice agents that
solve problems, not create them
Accurate transcription at unprecedented speed keeps voice agents responsive and reliable.
Ultra-low latency keeps conversations flowing naturally
Lightning fast transcriptions allows your agent to start thinking while the user is still talking.
41% faster median latency than Deepgram Nova-3 (307 ms vs 516 ms) and nearly 2× faster on P99 latency (1,012 ms vs 1,907 ms).- Delivers reliable, unchanging transcripts from the beginning so your system can act with confidence—even before the speaker finishes.
- Adjustable speed↔post‑processing dial to fit every use case.
Intelligent endpointing knows when to listen and when to answer
Combine acoustic and semantic features with traditional silence detection for smoother end-of-turn detection.
- Intelligent endpointing decreases end‑of‑turn delay versus traditional silence detection.
- Handles natural pauses without premature interruptions.
- Configurable parameters for everything from voice IVR to chat‑style agents.
Catch names, numbers, and nuance the first time
From addresses to account numbers, Universal-Streaming captures mission-critical tokens with unmatched precision—even in noisy or mobile environments.
- 21% fewer alphanumeric errors on email addresses, confirmation codes, phone numbers, and ID numbers.
- 28% improvement on consecutive numbers for accurately capturing phone numbers, confirmation codes, and account IDs without frustrating repetition.
- 5% improvement in proper noun recognition for names of people, products, and businesses.
Premium performance at a fraction of the cost
Go live with unlimited streams, enterprise-grade reliability, and pricing that stays flat—$0.15/hr, no concurrency caps or hidden fees
- Session-duration pricing starts at just $0.15/hr — charging for total session duration, not audio duration or pre-purchased capacity.
- Unlimited, autoscaling concurrent streams with no hard caps or over-stream surcharges.
- Consistent performance from 5 to 50,000+ streams without performance degradation.
Designed for voice-first experiences
Intelligent Endpointing
Customize End of Turn Detection to more accurately detect when one speaker finishes an utterance in Streaming Speech-to-Text.
Automatic Concurrency Scaling
Handle thousands of concurrent connections without manual intervention, eliminating the need for complex connection management.
Developer Toggles
Fine-tune the balance between speed and post-processing with configurable API options for timestamps, formatting, and punctuation.
Enhanced Visibility
Monitor streaming performance metrics in real-time with comprehensive analytics and usage insights.
Auto Punctuation and Casing
Automatically add casing and punctuation of proper nouns to the transcription text.
The speed difference is immediately noticeable - our users see their conversations transcribed almost instantaneously. It feels so much more responsive than what we were using before.
Ready to plug into your voice‑agent stack
Pre-built integrations with step‑by‑step docs enabling quick implementation without disrupting existing workflows.
Frequently Asked Questions
Streaming speech-to-text for voice agents is real-time transcription of live audio into stable text with ultra‑low latency, enabling agents to respond naturally. AssemblyAI’s Universal‑Streaming returns immutable transcripts in ~300 ms and includes intelligent end‑of‑turn detection using acoustic and semantic cues, so systems can act confidently without retroactive edits.
AssemblyAI uses a neural‑network turn detector combining semantic and acoustic cues. If end‑of‑turn confidence exceeds end_of_turn_confidence_threshold and brief post‑VAD silence passes, the turn ends; otherwise a VAD‑based max_turn_silence ends it. When triggered, responses include end_of_turn=true. Thresholds and silence durations are configurable.
Create an account and copy your API key. Install the SDK (pip install assemblyai) or connect via WebSocket. Initialize StreamingClient, set sample_rate (16 kHz default), subscribe to Begin/Turn/Termination events, then stream microphone audio. Always disconnect with terminate=True. WebSocket endpoint: wss://streaming.assemblyai.com/v3/ws with Authorization header.
AssemblyAI’s streaming STT for voice agents (Universal-Streaming) costs $0.15/hour. Pricing is session-duration based, meaning you’re charged for the entire time the connection stays open, whether audio is flowing or not.
Yes. AssemblyAI integrates with both LiveKit and Vapi. In Vapi, choose Assembly AI as the Transcriber provider (enable Universal Streaming). In LiveKit, use the LiveKit AI Agents integration to stream audio to AssemblyAI’s Streaming STT for real-time transcription.
Use AssemblyAI for real-time STT, then add your LLM and TTS, and orchestrate with LiveKit, Pipecat, or Vapi. For lowest latency, disable formatting (format_turns=false) and use AssemblyAI’s turn detection/utterance for pre-emptive generation. Start with the LiveKit or Pipecat integration guides.
Production streaming STT (Universal-Streaming) supports English by default. A multilingual streaming model is available that supports English, Spanish, French, German, Italian, and Portuguese. Additional languages are planned for late‑2025/early‑2026.
Turn voice data into unparalleled product experiences
Partner with the leader in Speech AI to build powerful products with breakthrough industry impact.
