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Research / Conversation Flow

SPX-MicroCFKnow when to speak. Know when to listen.

#1 in interruption recall. #3 in end-of-turn recall on TurnBench ↗.
From detecting speech to knowing when to respond.

VAD observes current activity and VAP predicts future activity; temporal decisions produce EOT and INT events
Fig. 01 · Current and predicted activity provide complementary evidence. Conceptual illustration, not an implementation or deployment diagram.
Download GIF ↗

On the official held-out TurnBench test set, MicroCF ranks first in interruption recall at 98.4% and third in end-of-turn recall at 90.6%. By combining current speech activity with predictions of future activity, it provides timing signals that voice applications can use to respond, wait, or yield the floor.

01 / Complementary evidence

Observe the present.
Anticipate what follows.

A pause can end a sentence—or simply mark a breath. Acoustic activity describes what is happening now. Conversational decisions also need evidence about what may happen next.

PRESENT

VAD · Current activity

Extracts speech-activity evidence from audio, grounding observations of speech and silence.

ANTICIPATED

VAP · Future activity

Uses the conversation observed so far to predict subsequent activity, providing context for continuation and speaker transitions.

The two views are complementary. Predictions use only audio already observed; they provide evidence for a decision, rather than constituting an end-of-turn or interruption event themselves.

02 / Temporal reasoning

Decisions with
temporal continuity.

The same brief pause can mean different things mid-sentence and at its end. MicroCF interprets observations within the ongoing conversation: current evidence and historical state jointly inform the next decision, rather than turning every transient change into an event.

st=Fθ(st−1,ot)Abstract state update: historical state and current observations jointly inform the decision.
Illustration · not measured · silent
UserI’d like tomorrow’smorning flight.
AgentWait for the user to continue.
KEEP LISTENINGA brief pause does not automatically end a turn.
03 / Asymmetric decisions

Know when to speak.
Know when to yield.

EOT asks whether the current turn has ended; INT asks whether another speaker is taking the floor. Both use activity evidence, but their errors carry different costs: responding too early cuts a speaker off, while yielding too late makes it harder for a user to redirect the conversation.

MicroCF treats these as distinct timing decisions, balancing detection coverage, false triggers, and waiting time for each task.

04 / Public evidence

Leading results.
Public evidence.

MicroCF achieves leading results on both core TurnBench tasks: first in interruption recall and third in end-of-turn recall. We report recall, false-positive rate, and detection latency together so the results—and their trade-offs—can be assessed.

INTERRUPTION · #1 IN RECALL
98.4%

FPR 7.3% · Median detection latency 747 ms

END-OF-TURN · #3 IN RECALL
90.6%

FPR 7.9% · Median detection latency 678 ms

Source: Official TurnBench test results ↗. Rankings are based on held-out test recall, checked September 23, 2026. Original-site screenshots are dated September 22, 2026. Detection latency is not full application end-to-end response time.

Conversation Flow

Speaking and listening, in context.

MicroCF provides conversational timing signals. Applications combine them with playback state and task context to decide when to respond, wait, or yield.

Explore the public evaluation ↗

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