# Controlling Backchannels in Streamable Full-duplex Models

arXiv: https://arxiv.org/abs/2609.29418 · HTML: https://mlsanity.com/paper/2609.29418/

## Key facts

- No citing papers in the map yet (data through 14 Oct 2026).
- Builds on 21 of its 25 references that are in the map.
- First posted on arXiv 24 Sep 2026.

## Builds on (most cited first, 21 of 21)

- [The Llama 3 Herd of Models](https://mlsanity.com/paper/2407.21783/) (2024)
- [LoRA: Low-Rank Adaptation of Large Language Models](https://mlsanity.com/paper/2106.09685/) (2021)
- [ECAPA-TDNN: Emphasized Channel Attention, Propagation and Aggregation in TDNN Based Speaker Verification](https://mlsanity.com/paper/2005.07143/) (2020)
- [Moshi: a speech-text foundation model for real-time dialogue](https://mlsanity.com/paper/2410.00037/) (2024)
- [Full-Duplex-Bench: A Benchmark to Evaluate Full-duplex Spoken Dialogue Models on Turn-taking Capabilities](https://mlsanity.com/paper/2503.04721/) (2025)
- [PersonaPlex: Voice and Role Control for Full Duplex Conversational Speech Models](https://mlsanity.com/paper/2602.06053/) (2026)
- [Canary-1B-v2 & Parakeet-TDT-0.6B-v3: Efficient and High-Performance Models for Multilingual ASR and AST](https://mlsanity.com/paper/2509.14128/) (2025)
- [SALM-Duplex: Efficient and Direct Duplex Modeling for Speech-to-Speech Language Model](https://mlsanity.com/paper/2505.15670/) (2025)
- [NanoCodec: Towards High-Quality Ultra Fast Speech LLM Inference](https://mlsanity.com/paper/2508.05835/) (2025)
- [Yeah, Right, Uh-Huh: A Deep Learning Backchannel Predictor](https://mlsanity.com/paper/1706.01340/) (2017)
- [Pearmut: Human Evaluation of Translation Made Trivial](https://mlsanity.com/paper/2601.02933/) (2026)
- [Multi-Faceted Interactivity Alignment in Full-Duplex Speech Models](https://mlsanity.com/paper/2606.11167/) (2026)
- [Yeah, Un, Oh: Continuous and Real-time Backchannel Prediction with Fine-tuning of Voice Activity Projection](https://mlsanity.com/paper/2410.15929/) (2024)
- [Sidon: Fast and Robust Open-Source Multilingual Speech Restoration for Large-scale Dataset Cleansing](https://mlsanity.com/paper/2509.17052/) (2025)
- [TurnBench: A Multi-Domain Benchmark for Turn-Taking Dynamics in Spoken Dialogue](https://mlsanity.com/paper/2608.25218/) (2026)
- [DualTurn: Learning Turn-Taking from Dual-Channel Generative Speech Pretraining](https://mlsanity.com/paper/2603.08216/) (2026)
- [VoXtream2: Full-stream TTS with dynamic speaking rate control](https://mlsanity.com/paper/2603.13518/) (2026)
- [Synchronization and Turn-Taking in Full-Duplex Speech Dialogue Models](https://mlsanity.com/paper/2605.20356/) (2026)
- [Endpoint Anticipation for Low-Latency Spoken Dialogue](https://mlsanity.com/paper/2606.13450/) (2026)
- [Multilingual and Continuous Backchannel Prediction: A Cross-lingual Study](https://mlsanity.com/paper/2512.14085/) (2025)
- [Aligning Backchannel and Dialogue Context Representations via Contrastive LLM Fine-Tuning](https://mlsanity.com/paper/2604.16622/) (2026)

## Abstract (arXiv)

Backchannels, brief acknowledgements like "uh-huh" produced while the other party may still be talking, are central to natural conversation, but full-duplex spoken dialogue models rarely model them explicitly. We introduce a lightweight backchannel head that predicts, from a full-duplex model's own hidden states, when a backchannel should begin. Once this probability crosses a tunable threshold, a backchannel is force-decoded. Attached to both a 7B (PersonaPlex) and a 1B (F-Actor) model, it generalizes across scale. Probing confirms the hidden states anticipate real human timing, and generation evaluation shows more frequent, better-timed backchannels. Human raters judge the resulting backchannels on par with real ones.