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there is a initial 3 second gap that we are observ...
# ask-ai
f
there is a initial 3 second gap that we are observing after everytime the agent speaks the first line. then after the 3 second gap post first line, then ongoing turns are smoother. but obviously this brings more hangups. why is this happening?
t
Thanks for reaching out, Manav. I'm an AI assistant and I'm here to help. Give me a moment while I research this topic.
Thanks — I understand you’re seeing a roughly 3‑second pause after the agent’s very first line (then turns proceed normally), and that this is increasing hangups. I’ll explain the most likely causes and give practical steps you can try. Why this happens (most likely) • The agent waits after speaking to confirm the user isn’t starting to speak. That waiting is part of turn detection (VAD + end‑of‑turn logic), which intentionally adds a small listening window so the agent won’t cut someone off. • The first turn often behaves differently because the system may be more conservative right after playback ends (the turn detector may extend its listening window based on confidence or semantic cues). That can produce a one‑time ~3s gap. • Cold‑start latency for audio processing (VAD not prewarmed) can add extra delay on the first interaction; subsequent turns are faster because components are warmed up. Practical steps to reduce or eliminate the gap 1. Check and tune endpointing delays ◦ Reduce 
min_endpointing_delay
to a lower value (for example 0.2s) so the minimum wait after speech is shorter. ◦ Verify 
max_endpointing_delay
settings so the detector won’t wait unnecessarily long on low‑confidence signals. 1. Review turn detection model usage ◦ If a turn detector model is active, test lowering its sensitivity for the initial turn or disabling model‑based extension for the first turn to avoid long listening windows. ◦ If you need help choosing which parameter on your agent controls that behavior, tell me which agent/runtime you’re using and I’ll point to the exact setting. 1. Prewarm VAD/audio pipeline ◦ Initialize VAD and any audio processing at agent startup so you avoid cold‑start overhead when the first line finishes. Prewarming removes the one‑time processing delay. 1. Instrument and measure ◦ Add brief logs/timestamps at: end of agent TTS playback, time VAD/listener enters listening state, and time first incoming user audio/frame is detected. This will confirm whether the extra seconds are from waiting logic or from audio processing. ◦ If you can share those timestamps (or whether you see playback end → listener start gaps), I can help interpret them. What I can help with next • If you tell me which agent config or runtime you’re using (and any current values for 
min_endpointing_delay
/ 
max_endpointing_delay
or whether a turn detection model is enabled), I’ll recommend exact settings to change. • If you can share logs/timestamps for one call, I’ll walk through them to pinpoint whether it’s VAD warmup or turn detector behavior. If you prefer, tell me: • Agent runtime or product name • Current endpointing settings (if available) • Whether you prewarm VAD on startup I’ll use that to give specific, step‑by‑step guidance. Sources: Turns overview | LiveKit Documentation | Improving voice AI's turn detection with transformers | How does end-of-utterance detection work in conversations? | Pipeline Translator Agent | LiveKit Documentation | How to match the latency of the homepage agent | LiveKit
f
i dont use vad
t
Thanks — that’s helpful to know. Since you don’t use VAD, let’s focus on the other likely causes and narrow things down so I can give targeted fixes. Quick summary of what I’ll address: you see a ~3s pause after the agent’s first line only (subsequent turns are smooth). You don’t use VAD. Possible causes when VAD is not used • Turn‑endpointing delays: The agent runtime may still use 
min_endpointing_delay
/ 
max_endpointing_delay
or similar endpointing timers to decide how long to wait after playback before treating the turn as over. Those timers can produce a one‑time longer wait on the first turn. • Turn detection model or heuristics: Even without VAD, a turn detector (silence/energy heuristics or a model) may be active and conservative on the first turn, extending the listening window. • TTS/playback completion to microphone/listener handoff: The pipeline that stops TTS playback and hands audio input processing back to the listener may introduce a cold‑path delay on the first transition (initializing the input stream, starting audio capture threads, or switching audio devices). • Networking or media setup on first use: If a new RTP/RTCP or media channel is established when the agent first finishes speaking, negotiation or jitter buffer priming could add delay. Next diagnostic steps I can guide you through 1. Check endpointing settings and turn detector state ◦ Tell me whether your agent config exposes 
min_endpointing_delay
or 
max_endpointing_delay
, or any "turn timeout" or "endpointing" parameter. ◦ Tell me if a turn detector model or an explicit "turn detection" flag is enabled. 1. Instrument timestamps to pinpoint where time is spent ◦ Add logs for these events (exact names you can use): i. TTS/playback end timestamp ii. Listener input start timestamp (when you begin capturing/processing mic input) iii. First upstream audio frame received timestamp (when the server sees user audio) ◦ Share those three timestamps (or the deltas). That will tell us whether the gap is in the client handoff, the server detector, or network/media setup. 1. Quick experiments you can try ◦ Pre-initialize the input/audio pipeline at agent startup so the handoff after TTS doesn't require starting threads or streams. ◦ Temporarily reduce endpointing timers (for example, lower 
min_endpointing_delay
to ~0.2s) to see if the pause shortens. ◦ If a turn detector model is enabled, try disabling it for the first turn or lowering its sensitivity. If you want, tell me: • Which agent/runtime or SDK you’re using (name and version). • Whether you have access to the endpointing settings mentioned above. • If you can run the simple timestamps log and paste the deltas here. With that info (especially the three timestamps), I’ll point to the specific setting to change or the exact pipeline step to prewarm so we eliminate the initial 3‑second gap.
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