ai-agent-book/slides/lesson-36.md

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theme	title	info	author	transition	mdc	lineNumbers	monaco	aspectRatio	canvasWidth	layout	class
seriph	Lesson 36 — When Should Voice Stop Taking Turns?	English video course for AI Agents in Depth	Bojie Li	slide-left	true	false	false	16/9	980	cover	cover

Expand · Chapter 9 · Multimodal Interaction

When Should Voice Stop Taking Turns?

Omni, full-duplex interaction, fast-slow thinking, and controllable speech

Lesson 36 of 42 · 19 minutes · End-to-End Omnimodal Models; Full-Duplex Models; Thinking Architectures; Human-like Speech

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The central question

How can an Agent listen, speak, interrupt, and think deeply without making conversation stall?

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Why this problem matters

Omni

Preserve prosody and emotion across one end-to-end model.

Full duplex

Choose listen/speak/stop actions many times per second.

Fast + slow

Keep interaction alive while a strategist works in the background.

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Three ideas to keep in view

Turn-based Omni

End-to-end audio but still waits for a turn boundary

Interactive model

Concurrent input/output with barge-in and backchannels

Latent bridge

Exchange richer internal state than plain text

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The book's visual model

Fast and slow thinking architecture alternatives

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Modular cascade vs. End-to-end/full duplex

Modular cascade

• Easy to debug
• Providers interchangeable
• Prosody lost through text

End-to-end/full duplex

• Lower boundary latency
• Preserves acoustic cues
• Harder to observe and control

The newer architecture buys interaction quality with reduced modularity.

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Fast interaction can delegate

intent = realtime_model.listen(audio_frame)
if intent.needs_deep_work:
    job = strategist.start(intent.context)
realtime_model.respond(interaction_state)
if job.ready: realtime_model.integrate(job.result)

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Test the claim

9-32 min

Test the end-to-end speech contract offline

Observe: Exact model contract, audio response handling, and fail-closed behavior without an endpoint

9-42 min

Audit controllable-speech media and listening evidence

Observe: 24 reference profiles, routed controls, media hashes, and the distinction from human MOS

Demo budget: 4 minutes · one contiguous terminal block

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Live demo

Switching to the terminal

$ python -m pytest chapter9/end-to-end-speech/test_step_audio.py chapter9/end-to-end-speech/test_none_content.py -q

$ cd chapter9/controllable-tts && python validate_artifacts.py

Run the command(s), narrate decisions, and point to the observation—not just the output.

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What the evidence supports

Finding 1

Full-duplex models replace discrete turns with continuous interaction decisions.

Finding 2

Fast-slow separation preserves responsiveness without forcing every answer to be shallow.

Finding 3

Voice quality must be judged from audio—not configuration labels or text transcripts.

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Where the claim stops

Boundary condition

End-to-end behavior is harder to attribute to ASR, reasoning, timing, or synthesis when a failure occurs.

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Engineering takeaway

Design rule

Choose the simplest voice architecture that meets the interaction target, and preserve modality-native observability at every boundary you remove.

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Continue the experiment

Step-Audio R1 upstream audit chapter9/end-to-end-speech/validation/upstream_audit.json Controllable TTS listening study chapter9/controllable-tts/validation/audio_quality_study.json Omni architecture comparison book-en/images/fig9-4.svg Step-Audio dual-brain architecture book-en/images/fig9-6.svg

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Pause and apply

Your turn

What should your fast interaction model be allowed to say before the slow model has verified the answer?

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Next · Lesson 37

Carry perception and action into visual interfaces, where every click changes the next observation.

→