Official documentation
Voice activity detection (VAD), OpenAI Realtime API
OpenAI, OpenAI Developers, n.d.
Read the originalRead on October 17, 2026
- What it is
- OpenAI's guide to automatic turn detection in the Realtime API, including the silence setting that decides when a speaker has stopped and which transcription models support it.
- How much weight it carries
- Official OpenAI documentation, current when accessed. Defaults and model support can change, so check the live guide before relying on them.
Facts taken from this source
- OpenAI says its gpt-realtime-whisper transcription model requires turn detection to be omitted or set to null, unlike models that default to server voice activity detection.
“gpt-live-transcribe and gpt-realtime-whisper require turn detection to be omitted or set to null” (Voice activity detection overview)
- OpenAI's Realtime API voice activity detection, its default server-side turn detection for models that support it, uses periods of silence to split the audio into turns.
“It uses periods of silence to automatically chunk the audio.” (Section on voice activity detection (server_vad mode))
- OpenAI's Realtime guide says that a shorter silence duration setting for voice activity detection means a turn is detected as ended more quickly.
“With shorter values turns will be detected more quickly.” (Turn detection settings)
- OpenAI says that a higher voice activity detection threshold requires louder audio to activate the detector, and so may work better in noisy environments.
“A higher threshold will require louder audio to activate the model, and thus might perform better in noisy environments.” (Section on voice activity detection, description of the threshold setting)
Pages that rest on this source
- Real-Time Speech Recognition: Streaming and LatencyGuide
- Can Whisper transcribe in real time?Question
- Voice Assistants vs Dictation: Siri, Alexa, GeminiGuide
- AI Voice Agents: How They Work and Where They FailGuide
- How do you connect speech to text to an LLM?Question
- How does speech recognition know when you stop talking?Question
- How fast does a voice AI agent need to respond?Question
- Turn detectionGlossary
- Voice activity detection (VAD)Glossary