How to implement intelligent turn-taking in AI voice using LiveKit?

All answers to this question.

LiveKit uses Silero VAD by default, but the key to a human-like AI voice is setting the right "prefix" and "suffix" silence thresholds. If you set the suffix too short, it cuts the user off; too long, and the bot feels slow. A pro tip is to use "Semantic VAD" if your LLM supports it. This allows the agent to look at the partial transcript and decide if the sentence is grammatically complete before it starts generating a response. I spent all of March 2024 tweaking these parameters for a tutoring app, and finding that "sweet spot" of 600ms silence made a world of difference.

   Answered 2025-05-12 by Cynthia Rogers

Does the framework allow for "thinking sounds" like "uhm" or "hmm" while the LLM is generating?

   Answered 2025-05-15 by Daniel Wood

• Yes, Daniel, you can absolutely do that. You can trigger a "thinking" audio track as soon as VAD detects the user has finished. This masks the LLM processing time and makes the AI voice feel more engaged. In the LiveKit Agents SDK, you can use the say() method with a pre-cached audio file of a filler word while the main generate_reply() is still streaming from the provider. I’ve found that even a simple 300ms "filler" reduces the perceived latency by almost half because the user hears something immediately.

     Commented 2025-05-18 by Kevin Hall

The barge-in feature is equally important. If the agent is wrong, the user needs to be able to stop it instantly.

   Answered 2025-05-19 by Ryan Mitchell

• Exactly, Ryan. Without instant interruption handling, the AI voice becomes a nuisance. LiveKit’s ability to "flush" the playback buffer is what makes real conversation possible.

     Commented 2025-05-21 by Heather Collins