late-flower-54951
07/06/2025, 5:10 AMvad
parameter on Agent) to break the audio into “speech” vs. “silence” segments.
• MultilingualModel (an EOUModelBase
implementation) as the turn_detection
component on AgentSession
, which runs LiveKit’s “end of utterance” transformer on the text transcripts to decide when the user’s turn has finished.
By default, LiveKit will:
• Stream incoming audio through the VAD plugin, emitting “speech” and “silence” events.
• After a silence event of at least min_silence_duration_ms
, invoke the EOU model on the accumulated transcript to confirm that the user really has stopped speaking.
• Only once the EOU model signals “end of turn” does the pipeline send the final transcript to the LLM and TTS.
Because of that two-step process, we’re seeing 1–1.5 s of “dead air” between the user’s last word and the agent starting its reply—even though our LLM TTFT (~250 ms) and TTS TTFB (~230 ms) are already rock-solid.
Questions:
• Is my understanding of the LiveKit pipeline correct—i.e. that Silero fires on silence first, and only then does MultilingualModel run on the final transcript?
• Are there configurations or best practices to reduce this gap? For example:
◦ Running the EOU model continuously on interim transcripts instead of waiting for a full VAD silence event?
◦ Tuning Silero’s min_silence_duration_ms
lower (e.g. 200–300 ms) versus relying on MultilingualModel’s own thresholds?
◦ Adjusting MultilingualModel’s unlikely_threshold
or other parameters to detect end-of-utterance more aggressively?
• Does the LiveKit documentation include any examples or recommended settings for achieving sub-700 ms total “user-silent to agent-speaking” latency?
Any tips, example settings, or success stories for sub-1 s total response time would be hugely appreciated!tall-airline-16756
07/06/2025, 5:10 AMtall-airline-16756
07/06/2025, 5:10 AMmin_endpointing_delay
parameter, which defaults to 500ms, can be lowered to make the agent respond faster. However, this might increase the risk of interruptions.
• Configuring the turn detector model: The unlikely_threshold
parameter can be tuned to make the end-of-utterance detection more aggressive. This threshold can be configured per language.
• Semantic turn detection: The transformer model used for semantic turn detection leverages the content of speech to predict when a user has finished speaking. Fine-tuning this model might also help in reducing latency.
Unfortunately, the documentation does not provide specific examples or recommended settings for achieving sub-700 ms latency. However, experimenting with the above parameters and configurations could help you optimize the response time. If you have further questions or need assistance with specific configurations, feel free to ask.
Sources: Improving voice AI's turn detection with transformers